TRAVEL INSIDER : Loire Valley Lodgings for Under $40 a Night : France: ‘Ultra-budget’ chains offer comfortable, clean rooms and high-tech reservation services. The drawbacks are their commercial settings and limited desk hours.

I celebrated the arrival of spring this year in the lush region of France known as the Valley of the Kings, wandering the forest trails and village lanes and gaping at the centuries-old royal chateaux along the meandering Loire River.

Some of these centuries-old castles now are grandiose guest houses, with rates in keeping with their regal past. But my own lodging during this weeklong dip into the lifestyles of the landed gentry cost an average of $33 a day--and even had advantages over Louis XIV’s drafty old Fontainebleau.

These bargain digs weren’t Spartan hostels or grungy truck stops, either, but stylish links in rapidly expanding chains of French budget motels.

With a credit card, guests can check in 24 hours a day via a high-tech “reception automatique “ that looks and works something like a cash machine. You “converse� with it (in English, French or German) about your room needs and length of stay. On your receipt is a personalized six-digit code that you punch in on key pads to get into the building and your room. The managers of these “ultra-budget� chains live on the premises and are available in emergencies, but staff the front desk for only the few busiest hours morning and evening.

At the motels I visited, daily rates ranged from $24 to $48 (prices sometimes vary by season or location; highest rates tend to be for Paris motels, no matter what the season). In many cases, the same room rate applied for single, double and even triple occupancy.

The motels were all attractive inside and out, with flower gardens and lobby bouquets. Four had gabled roofs that made them look like overgrown French farmhouses; two were dramatically modern. Rooms all were spotlessly clean, quiet and featured color TVs (usually with a remote and in one case also a VCR), as well as guest-controlled heating cooling units and automatic wake-up systems. Most also had private baths and phones. Decor was functional--sort of early college dorm, but Ivy League--and there was an overall quality that Madison Avenue might term “European elan.�

Three of the motels offered all meals (at additional cost), and those that didn’t were located next door to a restaurant or a hotel with a full-service dining room. Most also had snack machines. At all, a breakfast buffet was available for $4 to $6--somewhat stiff for a cup of coffee and rolls served in a lobby alcove, but a few places also added yogurt, fruit, cheese and cold cereal.

Most guests probably welcome an on-premises eye-opener at any price because of the typical lack of charming cafes in the neighborhood. If the motels shared one flaw it was their locations--always handy to auto routes but surrounded by a moat of light industry.

I started my chateau touring near Orleans, about 150 miles south of Paris, and meandered in a long oval that embraced the Loire, which is sort of the Mississippi of France.

Around 4 or 5 p.m., I’d check the motel directories I’d sent for before leaving home to see which chain had a branch nearby. Here’s a closer look at my choice of motels, starting with the most expensive:

Hotel Climat de France: At $48 for one or two people (a third person was about another $5), Climat was my most expensive overnight stop. At the motel north of Orleans, the young woman at the desk seemed to speak no English, but when we reached an impasse she cheerfully played 20 questions in French (Was I trying to ask the cost? Their checkout time? The dinner hours?). The building looked brand-new, and the next morning a different clerk was able to explain that, indeed, the motel had been open only three months.

My room had a cheery blue and white color scheme, and besides the TV there was a phone and a VCR (videos cost 30 francs, about $6 each, from a machine in the lobby). The private bathroom had a tub-shower and its own heater. Down the hall was free coffee, tea or chocolate. My $20 dinner at Climat’s attractive La Soupiere restaurant off the lobby was the highest-priced of any of the three motels with dining rooms, but still was nearly half the price of a comparable meal at many independent restaurants in the Loire area. The breakfast buffet, about $6, also was the priciest, but included juice and fruit.

For a directory or reservations, contact France Vacations, 9841 Airport Blvd., Suite 1120, Los Angeles 90045, (800) 332-5332; or write Hotel Climat de France, 5 Avenue du Cap Horn, BP 93-91943 Les Ulis Cedex, France.

RestHotel Primevere: At about $40 for one or two people (a lobby sign noted that the high-season rate was about $5 more), the pretty motel where I stayed on the outskirts of Blois also had a pleasant restaurant, and desk clerks and waiters spoke a little English. My room was similar to the one at Climat, though the dominant color was red, with a color-coordinated Matisse poster from the Hermitage in St. Petersburg. The bathroom again had its own heater, but just a stall shower instead of a tub. A comparable dinner was about $5 less than at Climat. Unfortunately, I’d misunderstood the breakfast hours, and every trace was gone when I arrived.

For a directory, write RestHotel Primevere, BP 66-91223 Bretigny-sur-Orge Cedex, France; or call 011-33-1-69-01-97-60.

Aster: The motel I tried on the outskirts of Paris, at St. Germain les Corbeil, best pulled off the country-guest-house-that-you- almost-forget-is-in-an-industrial-park ambience. At $38 a night for one or two people (third person $12 extra, $6 for a “supplement animal�--ah, the dog-loving French), it was my all-around favorite as a traveling American.

For a directory, write Aster, 18 Rue de la Tuilerie, BP 102-37551 St. Avertin Cedex, France, or call 011-33-47-80-38-05.

Mister Bed: Basic, to be sure, but so inspired that at $27 a day for up to three persons ($9 for a fourth), it was the all-around value winner. At the motel I chose near Tours, breakfast ($4.50) was a lovely presentation of juice, yogurt, cheese, cereal, rolls, drinks and fruit that even extended to kiwi and a whole coconut. It was laid out amid plain, yellow-topped tables in the rustic modern, redwood and glass two-story lobby, which was open to the roof and brightened by facing window walls. The motel was just 7 months old, I was told by a charming young man at the desk who went far beyond the call of duty in complimenting my French pronunciation. Room decor was yellow and forest green, and the furniture, though simple, had a pizazz missing in most American chains, especially those at the bottom price range. The modular private bathroom relied on the room heater, but had a fabulous shower. Though there was no restaurant, vending machines offered snack fare plus meals to heat in a microwave.

For a directory, write Mister Bed, 32 Rue Pierre Curie, 92000 Nanterre, France, or call 011-33-1-46-14-38-00.

Hotel Formule 1: At $24 for one, two or three persons, this was the cheapest of the accommodations I used and probably also the most ambitious.

At the motel in Bourges, the desk clerk took great care to explain (in French) that things were pretty basic. My room had a bunk bed over the double bed and a TV, but no remote control. The biggest drawback: no bathroom, only a sink in the bedroom. Shower cubicles and lavatories down the hall again were automatically disinfected after every use.

For a directory, write Chaine des Hotels Formule 1, Immeuble le Descartes, 29 Promenade Michel-Simon, BP 159-93166 Noisy-le-Grand Cedex, France.