A good wedding reception playlist will have high moments and low moments- fast songs and slow songs. Times for people to dance close, times for people to slow dance, and even times for people to go get a drink so they can enjoy the dance floor even more.
If I had to give you a ratio, I would advise playing about 90% upbeat/dance songs against 10% slow jams. Or maybe every 10-12 songs, throw in a slower one. People want them… just not
2. Keep it 90% Fast Songs, 10% Slow Songs