Without knowing the members of your party, I’ll make some various suggestions:
Character meals -
Chef Mickey’s at the Contemporary Resort
1900 Park Fare at the Grand Floridian
Fun meals -
Whispering Canyon Café at the Wilderness Lodge
Rainforest Café at Downtown Disney
‘Ohana - Polynesian
Upscale dining -
Artist Point at the Wilderness Lodge
California Grill at the Contemporary Resort
All of these restaurants would be fun for a first evening. The character meals are a nice way to start a WDW vacation. Since they are both on the monorail line, you could take a round trip ride before or after your meal.
Any meal at Downtown Disney would also allow you to walk around this fun entertainment district too. Dining at the Polynesian or Grand Floridian resorts would give you the opportunity to watch the evening Wishes fireworks. Enjoy your dinner, do some shopping, then walk outside to watch the fireworks.
I like our first night to be low key as we are usually tired from traveling and hoping to get an early start the next morning.