We love Cali Grill date nights so we can watch the fireworks together.
Once we did Trader Sam's at the Poly for drinks and appetizers, then had a romantic stroll around the Poly, then we took the monorail to the CR for a Cali dinner. That was really fun because we met other couples at TS's and laughed and talked with them.
Another night we had a nice, early dinner at WL and then headed to Cali Grill later for dessert, drinks, and fireworks.
Just be aware that if you have to use childcare, it can take a very long time to use boat transport around the lake (if you are leaving kids at one resort and visiting another). We took the boat from the Poly one night to MK and then took a boat from MK to WL and it took us over an hour to do that- by the time we waited on boats. If you have to use Disney transport, factor in a lot of time for that.
We haven't done it, but I also think that a date night at AKL would be very romantic. I just find it to be a lovely resort. Dinner at Jiko followed by a stroll, relaxing by the fire, then some night goggles animal viewing and some drinks would be a romantic date night.
If you can afford it, the Wanyama Safari dinner is one of the most romantic things to do at WDW. It used to be offered only to AKL resort guests, but I think they have opened it to anyone now.
You can also do the Savor the Savanna Experience at AK park. You just also have to purchase a theme park ticket in addition to paying for the tour.
So many wonderful date night options at Disney!