Sherwood Gardens might be a good option for an outdoor thing. The tulips probably won't be out quite yet, but there will be other things blooming.

If it's rainy, you could also visit Rawlings Conservatory in Druid Hill Park. It's a beautiful building, with a 19th century glass palm house. There is a suggested donation of $5/person. I like to go there when it's overcast to get a little sunlight without getting dripped on.

Idk if the spa at the Four Seasons downtown is in scope, but there are great water views there and it comes highly recommended