Hi kristin, welcome to BDW :0)
I haven't been to the Melia but I have been to Dreams Punta Cana and it is a large, beautiful, upscale resort. A great choice for a DW. They're pretty popular and sometimes have as many as 3 DW's a day but there are different ceremony locations to chose from. Your travel agent should be able to compare the 2 resorts in size I'm sure.
happy planning!