The 2 meter band (144-148 MHz) is by far the most popular ham band in the US. The 70 centimeter band (420-450 MHz) is second. Six meter is not so popular; you can get longer range but it doesn't always have great propagation and not as many people use it. There is no 4 meter ham band in the US. See http://www.arrl.org/files/file/Hambands_color.pdf for more information about amateur license privileges.

I'd suggest a Technician license and a 5 watt dual-band (2M/70CM) HT. Add a longer antenna to it and you're likely to find someone to talk to. I bought inexpensive ones (http://www.universal-radio.com/catalog/ht/5547.html) for my wife and my daughter when they passed their Tech licenses. There are certainly better HTs out there but this one works well with good audio, it's hard to beat for the price. Note that you'll be much happier if you buy a programming cable for it (I have an aftermarket USB cable for programming Kenwood HTs that works perfectly).

I've been to some reasonably remote parts of CONUS that had good coverage from active 2M and 70CM repeaters.

A two meter mobile rig with 30-50 W of power and a good antenna can give you significantly improved range, and they make man-portable and mobile HF rigs that will let you talk to someone in China if conditions are right. Keep in mind that you need at least a General license for the best HF privileges.

Take a look at http://www.kb6nu.com/wp-content/uploads/2010/06/2010_Tech_Study_Guide.pdf to see what you need to learn to get a Tech ticket.

I'm a member of the ARRL, a General class radio amateur, and a customer of Universal Radio, Kenwood and Wouxun. Otherwise I have no affiliation with anything mentioned here.