I have to agree with the other posters here, i'm a long time Marriott (and many other chains) user and Marriott is the MOST consistent within brands of any hotel company I have stayed.
Although SPG is a great program, you just don't know if a Sheraton is going to have a lounge or not. With marriott, if it's a FS marriot and not a resort (normally resort appears in the name) then you're going to get lounge access during the week. Sure, some do it on weekends, but that's a bonus.
True, some hotels go out of there way to provide a much nicer breakfast. When all this started, the lounges provided a cold breakfast. Slowly over time, some hot items have been provided and some hotels do a much better job than do others. Personally, I'd prefer the buffet downstairs, but lounges can be quick.
Evening snacks can range from nasty to a full meal. Really hit or miss, but always there.
The worst I've found with respect to consistency are Fairfield inns. Some are fantastic, some OK and a few - well - they don't belong in the Marriott chain. That's my main reason for being a bit wary of them.
The "new" courtyards are very nice (as are the Hyatt Places) - too bad all of them haven't upgraded.
Billy