Daytona is a shithole IMO. I went with interns from work, which was the ideal venue for that (drunken skinny-dipping screaming/yelling madness), but as far as restaurants and entertainment goes...there are 2-3 ok restaurants at the pier (bubba gump shrimp, a burger place and...actually, there are only 2 okay restaurants and one of them is a franchise) and nothing else much to do? They had some fireworks one night...Beer special another.
Overall, I think there are much nicer beaches in Florida. Also, not to forget that cars are allowed on Daytona beach, which are loud and kick up sand and such. Not the ideal venue to go with your girlfriend.
Disney is great, especially with your girlfriend. Book an extra day there instead and try to stay on the Disney resort, their transport system rivals most public transit systems (including Montreals).
If you're not staying at Disney, hotwire a room nearby. For the last night before we left on our cruise (which is also a good thing to look into) we hotwired a room near Disney (right outside the park) for $40, and it was actually a really nice hotel.
Premium outlet mall is also a must, even if you don't like shopping. Your girlfriend will trip over that. I got a couple pairs of 7 jeans for $80 each I think? Ralph Lauren stuff ultra cheap, etc.