Okay, actually ... on second thought, I need to clarify some stuff.
1) the iPad will pick up T-Mobile 3G HSPA+ if the area has been refarmed. I'm not sure if Las Vegas has. T-Mobile has HSPA+ on the 1900mhz band, but they're slowly moving it to a band that the Apple devices will support.
I'm not sure your area has already been refarmed. If it has, it'll pickup T-Mobile HSPA+. If it hasn't, it still will work, but on Edge which is really pointless.
2) I'm assuming if you get it activated and put the SIM in, it'll be fine. I believe that the plan you're referring to is the one that includes voice and text so I had my initial concerns considering it's really a phone plan, that it is for. But I've put the SIM from my AT&T iPhone that has a texting/voice plan on it too, and the iPad worked just fine for that.
You can check if iPad comptaible 3G is in your area here
http://www.airportal.de/