Been together with my GF for 3 years - only got her flowers ONCE (and it wasn't to apologize for something). That's just my girl though... she understands me, and I know she really REALLY appreciates things i "never do." The main thing is that it comes from the heart.
Interesting thread here, folks... sure hope you're simply looking for guidance, neovan, not just some list of items that you'll start ticking off, treating present-giving like a chore.
When she asks, "wow! how did you come up with this?" I'm not sure she'd want you to say ATOT.
Although I agree with the bit about getting an enagement ring since you guys are > 5ys, I wouldn't suggest it. That's the sort of things that comes from you... and if that idea doesn't leap out at you, is it really worth doing at the moment? Your GF wouldn't want you to get her a ring if it was because you felt you "owed it to her."
I think the "vacation" idea is best... but I know the money's tight (when isn't it?), just make sure to emphasize it as a well deserved celebration for a completing the task. Perhaps a weekend where she doesn't have to worry about the mundane tasks of day-to-day living.
If you want to really make it special... serve her hand-and-foot: breakfast in bed or candlelight dinner (dressed in a nice suit) are a few ideas. Of course, lots of hard work on your part, but I'm sure she'll never forget it... plus it's something you can do it at home... you get the idea.