Yeah, I know ... My oversea plan is very simple & inexpensive, and I have 2 mobile numbers on a single Sim card. Within the greater LA area and Vegas, coverage between T-Mo and AT&T are about the same, one is less expensive than the other (notice that I didn't use the term economical) For that, I reserve it for our triple bundle of fiber optics broadband, HDTV and feature-riched home calling, and that's cheap in comparison.

If you are planning to shop at the Tanger Outlets in Barstow, CA - you should know that it has free WiFi all over the mall while you shop, just aim your fav. app at those bar code & click ... to help price comparison shopping - so you would not need a lot of data. http://www.tangeroutlet.com/barstow/directory

3G speed is fine - using that on my HTC global smartphone and it's plenty fast, good enough to stream youtube while waiting. If you do end up with T-Mo and get the micro-Sim card kit to activate it, you are free to switch among the 3 Pay-by-the-Day plans, from the $3 to $2 to $1 and back again - but do not go back & forth on the same day or you will be pro-rated and end up paying twice within a 24 hour period, some users reporting on a different forum.

We have a trip heading out to West: LAS, SFO & LAX next month and will check out coverage as we hit the freeways - can't say we look forward to 8 to 10+ lanes of traffic in southern CA around the clock, LOL.