Boingo's roaming association is with Wayport and Laptop Lane (and now a few but growing number of regional airports such as GEG), which seems to be more hotel and to a lesser extent, airport oriented. Boingo/Wayport is significantly behind in number of locations compared to T-Mobile, but is a great "second place" wireless service IMHO.
T-Mobile has partnerships with Borders Books, Starbucks and Kinko's locations...I think there's a deal brewing with adding shipping stores like FedEx or UPS...not quite sure yet). T-mobile is also expanding its' international operations and has locations throughout parts of Europe.
I currently subscribe to both services and have for over 15 months; I find each to be indespensible while on the road. If you have $55 a month (I use Verizon for wireless, so no $19.99 deal for moi) to spare on the company budget and are on the road a fair amount like I am, they're worth every penny.
The 10K miles from T-Mobile, FWIW, took about 8 weeks to post the bonus to my AAdavantage account last year.