Looking for safe and cheap hotel along I-15 (or nearby) (Pocatello: fit in, hotels)

[nambis]

I will be driving from Canada to Tucson and plan to get a hotel in Idaho Falls, Blackfoot, or Pocatello. I will have a small car filled with pretty much everything I can fit in it. I am kind of worried about a break in, but I do plan to take the "valuable" things into the hotel with me.

Anyhow, can anyone recommend a hotel in Idaho Falls, Blackfoot, or Pocatello along I-15 that has reasonable rates and a safe parking lot (where my car is less likely to be robbed)? I'm a single guy and I don't need a fancy room, heck a semi-trashy motel would even work (as long as the air conditioning is good).

In general, is there a price difference in hotels between these 3 cities, or are they pretty much the same?

Thanks!

EDIT: Oh, and this will be at the end of August, if that makes a difference.

Also, are hotels especially busy during that time of year? Should I book a room in advance, or can I find something when I drive in?

[pw72]

Super 8 along Lindsey exit 118 (left turn), and Motel Six (right turn) off the same exit. Safe, decent rooms, reserve ahead on-line for best rates.
Plenty of fast food nearby.

[cleosmom]

Same exit going West (right turn) is Motel West. Nice, clean and locally owned, rates run about the same as the Motel 6 and Super 8 and it's just past the Motel 6 on the right hand side.

I would also suggest getting a reservation in advance, end of August can be close enough to Labor Day to make a difference in getting a room