If you're moving to Seattle, then T-Mobile and Cingular/ATT are going to be the two primary choices for GSM compatible phones. The two big differences are cost (T-Mobile is a bit cheaper) and data rollout (Cingular/ATT already has 3G up and running, T-Mobile is still testing).

That said, the most important thing is going to be coverage quality. All carriers in the US are required to accept a 14-day return (in some states it is 30) on any service plan without early termination fees. This is designed so that you don't sign up for service and then suddenly realize it doesn't work someplace important to you. Two year contract terms are standard, though if you go into a store you can get a one year contract at least with T-Mobile. I believe Cingular/ATT still offers the one year option as well, but don't know if that changed since the official switchover to ATT.

For the most part coverage is good, but *EVERY* carrier in the US has dead spots so DO NOT trust anyone who claims carrier X *always* drops calls. Call quality is going to be a factor of coverage and phone hardware so the best advice I can give is test it out for yourself when you move here.

As for SMS/MMS you are correct. Texting is only starting to catch on here. It is nowhere near as popular as it is in Europe, in part because it's just so darn cheap to make a call. Without a text option, SMS/MMS typically cost around $0.10-0.15 to send and to receive. Some carriers (or pre-paid options) will be more or less. All carriers offer some sort of messaging bundle which typically includes a certain amount (or an unlimited amount) of SMS/MMS messages. This can be an add-on, or included in the default plan so shop around.

Using a mobile phone instead of a landline is very popular in urban areas of the US. Most people I know don't even *have* a landline anymore, though a few have more than one mobile line. I personally gave up my landline a few years ago and haven't looked back. Cell minutes are so cheap there is little reason to have a landline. It just doesn't make sense.

3G technology has been rolled out in the US with CDMA carriers using EVDO and GSM carriers using UMTS/HSPDA. The key bits here are:

T-Mobile: Still in test, is planning on using a 1700 Mhz carrier for the 3G signal. This means no existing 3G handset will work with it in 3G mode (only standard 850/1900 GSM/EDGE mode). T-Moble runs its main GSM network on 1900, though offers some service on the 850 band.

Cingular: Uses 850/1900 for 3G as well as GSM/EDGE. Cingular runs its main GSM network on the 850 band, but offers some service on the 1900 band. This is used throughout the US, but not in Europe where 2100 Mhz is used. In Aus Telstra launched its 3G GSM service on 2100, but is switching to 850 (which it is branding "Next G"). If you have an existing Telstra (or other brand) GSM phone that you like, you can always get it unlocked and use it here in the states. If it is one of the "Next G" phones it should work on Cingular's 3G network.

The only real "limited" part of 3G deployment is limited by the sheer size of the US. In urban areas and near cities, you'll find plentiful 3G coverage. Out in the boonies, not so much. Between my personal and work lines, I've typically got a phone on every major carrier and to be honest, they all have excellent coverage, even if you do a lot of domestic travelling. Roaming agreements have gotten pretty extensive domestically and it is unusual for a major US carrier to charge for roaming, so most customers don't worry about it and just use the phone as they see fit.

Finally, your question about "advanced" phones ties in a bit with the above infrastructure comment but also the American attitude towards mobiles. The minutes are cheap and plentiful, so the majority of people in the US see it as a phone. There is also a large expectation of cheap or free when signing up for a plan which means the majority of phones offers by carriers are on the low cost part of the scale. Combine this with carrier subsidies and the typical US customer thinks that a phone (sans any sort of service plan and the associated subsidy) is a total rip off. Tech savvy folks are of course the exception.

Independent cell phone stores exist, but they are not the norm. You won't find large stores selling just phones. Rather they are going to be smaller, local shops that sell a selection of carrier branded phones as well as unlocked phones either from abroad or direct from manufacturer. The majority of cell phone stores in the US are carrier branded stores selling carrier branded phones so you'll go to a "T-Mobile" store or a "ATT" store most likely.

Another oddity in the US is the concept of a SIM only plan. Yes, you can just purchase a service plan without a phone. No, the retail jockeys at the major stores have *NO* idea how to process the order in their systems. It is often much easier (assuming you have a phone you like) to simply sign up for the service plan you want, take one of the free phones and then resell the handset on eBay.

Pre-paid SIMs run a similar concept. If you want to go pre-paid, you'll typically have to buy a "starter pack" at one of the two majors that includes a phone and SIM (cheapest option is usually around $30 US when on sale). Buying a pre-paid SIM by itself will usually run MORE money. Yes, it makes NO sense, but the US market has always seen pre-paid as something of a side market and never really catered to it like carriers abroad. Thankfully some independent shops will sell pre-paid SIMs cheaply, as it is cost effective for them to split the starter packs and sell the handsets separately.

Hope all that information helps. If you need anything else, just let me know.