I use a Lenovo T500 primarily in and around San Francisco, although I do some travel in the US on business and occasionally to Europe/Asia. I'm looking for a good mobile broadband option for my T500. I am admittedly baffled by the various mobile-broadband choices (3G vs. 4G, WiMax vs. LTE vs. MIMO vs. ..., etc.). My priorities are (in this order):

1. Compatible with Lenovo T500 and Windows 7. I realize only the AT&T accessory card is listed on Lenovo's site, but I've also heard that other cards will work in my T500 too, like the WiMax/Wifi combo card-- so I'm interested in what actually works, not necessarily only what Lenovo is promoting.
2. Reliable coverage in US large cities, especially the SF Bay Area. my IPhone has lousy coverage in many spots, so I'd be nervous about an AT&T 3G option unless the problem is with the IPhone and not AT&T's network. I'm OK with non-great coverage outside major US cities, since I don't do much travel in those areas.
3. Speed. faster is better.
4. Internal card. I'd slightly prefer something I could install inside my T500 instead of a dongle on the side that might break off, although this is my lowest priority so it's not a big deal.
5. Price. I don't want to pay over $100/month.

I've tried lots of Googling and haven't come up with clear answers. I've seen lots of general overviews without recommendations, and lots of passionate opinions which don't feel objective (and don't help me understand compatibility with my hardware & geography).

Can you recommend a good, objective guide online, ideally for Lenovo although general guide is OK too, which can help me figure out which option is the best one for me?

I'd also be interested in your own personal experiences of using mobile broadband using a Lenovo T500.

I'll accept the answer which gets me closest to making a decision.