My husband and I just got back from our honeymoon in Disney, it was our first time as a couple there, too! We used the dining plan, and I'll never again go without it!!
Our favorites were:
California Grille (Those nighttime fireworks were spectacular, and the food was absolutely delicious) - 2 TS credits (it's worth it!)
Boma (YUMMMMMMM is all I can say about this buffet!!)
Crystal Palace (it really made us feel like kids again - Winnie the Pooh and friends go around and mug for the camera! - plus the food was very good for a buffet!)
Raglan Road (It's not on the "approved" list yet for Downtown Disney, but I'm assuming it will be soon - the atmosphere was sooo fun, the food was absolutely delicious - I highly recommend the "It's Not Bleedin' Chowder!")
We actually had lunch at Coral Reef, we didn't like it very much - we waited for an hour and a half for our table (yes, we booked ressies ahead of time, and another group ahead of us had waited 2 hours for their table), the food was overpriced (even for the plan) and small portions... I even found a bone in my fish, yuck! Their lobster salad was warm and soup was lukewarm... but the atmosphere was gorgeous, so it's really a toss-up.
We didn't really like Les Chefs de France either, the steak was tough and the duck was cold, plus it took almost 3 hours to eat there, we had ressies at 6:15 and we STILL missed Illuminations, even though we tried to emphasize to the waitress that it was our first time seeing it!!
We did the Fantasmic Dinner Package with the only available restaurant, Mama Melrose - and I thought some of the food was really good, it was a nice little spot in the back of DHS, so it was quieter for a couple!
I hope this helps!!!

Have a terrific time, whatever you decide to do, it'll be amazing, I'm sure!!!