It also took a long time for me to warm up to Steam. I used to live pretty much in the boonies in Italy and I only had dial-up internet access. So every time I installed a Valve game (back then I only used Steam for Half-Life etc.) I had to wait for it to install then download megs and megs (gigs maybe) of updates on a 56k dial-up before I could even play the game. I was not happy.
You don't need to go online with Steam to play a game, unless the game specifically requires it (like the Ubisoft games). Steam does have an offline mode, even though its completely illogical. When you're signed into Steam online you can go to the Steam drop down menu and select "Go Offline". Steam will restart in offline mode, and you can play all the games offline that don't specifically require a connection. It will start this way until you go back to the same menu and tell it to go back online.
The offline mode works, but it's really badly implemented, since you basically have to know when you're online that the next time you're gonna login you want to be offline, because you can only activate offline mode while connected to the internet. I made that painful experience on day when I came home and the internet was gone. I couldn't sign into Steam, because I couldn't go online to go offline!
Somebody explain to me how that makes sense! Usually when you start Steam in offline mode it's because you can't go online!
I'm not much of a multiplayer gamer either, so I don't need my games to be online.
The problem with DLC is that they sell the main game at full price, plus you have to pay for DLC. I bought Saint's Row The Third in the summer sale and the amount of DLC for that game was absolutely ludicrous. A metric ton of extra outfits and cars for like 1,99 each (at normal price). No. Just no.