I don't think it matters. We always do online checkin because I feel like there is more chance of having the room ready early and getting our requests. Last year at AKL, we had a split stay - DVC room for a few nights, then a regular lodge room. Both standard view. And we were given savannah views both times, with online check in. (DH says if we stay there again we have to book the savannah view, now that he knows what he'd be missing, lol!)
Then in October, the CM at POR tried very hard to upgrade my parents to a Royal room, but there were simply none available. But checking in online had no effect on it. A lot depends on the CM doing the check in, and obviously what's available. I definitely wouldn't count on getting more than you book though.