While I agree that upgrades to suites are possible at Starwood...they're not necessarily likely. The really nice Starwood hotels (or resorts) do have some fantastic suites, but your run-of-the-mill Sheraton/Westin/Le Meridien typically offer junior suite upgrades--if available.

Also, very few Starwood club lounges offer free drinks in their club lounges. I only mention this because I think this is one area where Hilton clearly beats SPG. Starwood doesn't offer Platinum members free drinks (a pet peeve of mine, since the majority of Hilton, Marriott & even some Crowne Plaza hotels do).

I say this as a loyal SPG member, but if I weren't as entrenched in Starwood, you may want to think twice about Hilton. Many of their elites jumped ship last year (due to a point devaluation), leaving the remaining members able to get more perks! If there are good Hilton hotels near where you'd travel, I think (if I were you) I'd probably stay with Hilton.

The big differences in the programs (as I see them) are that Starwood offers the potential for great suite upgrades at some hotels, but Hilton almost guarantees upgrades at several of their brands, while also guaranteeing breakfast & often free booze. If I were starting out as a frequent traveler today, that sounds pretty enticing to me!