Hi there, Kolby!
Disney's
Be Our Guest Restaurant in New Fantasyland does offer both lunch and dinner seatings.
Lunch, as you point out, is Quick Service, and you do seat yourself. However, in order to maximize the number of lunchtime diners, the Rose Gallery dining room will only be open during lunchtime.
While there is no way to really predict the crowd levels at lunch, you can likely anticipate a bit of a wait. Perhaps going at "off hours" would minimize some of that: perhaps a very early or late lunch would allow you miss peak lunchtime dining crowds.
Have a wonderful time - and bon appetit!
See you later, celebrator,
-Deborah B.