I feel bad that no one has responded. I have been out to DL a few times but I don't know it well enough to really help you. I would do something in the original park over the Cali park b/c I think its more romantic. I dont' know if its still there but there used to be a great little breakfast place on mainstreet with tables outside sort of inbetween the shops. I am not sure thats the place to propose but it might be a fun way to get the day started. You def need a reservation. Hopefully a DL bride will come along soon, if not I would just call the DFTW dept in CA and ask them for help. I am sure there are a number of packages that you can purchase.
I would also consider dinner reservations at either Napa Rose or if there is any way that you can get into the secret club in DL that would be cool. Before I thought it was only an option to passholders and you had to pay yearly dues or something - I could be totally wrong. Since we don't live on the west coast we never joined and so I don't know much about it.
Just thinking back there used to be a restaurant inside pirates of the carribean that had a lot of atmosphere - if you wanted to stay in the park and couldn't get into the club then thats what I would choose.
All of these memories coming back! Ok so if it were me working on the little knowledge I have. I would try to get a fantasmic dinner package (if they have them in dl?) and then propose at the end of fantsasmic - when sorceror mickey suddenly appears at the top of the mountain dressed in his hat and robe. Its my favorite part of the show - thats what I would do.