A host is busy—hosting—and flowers in a wrapper require attention.
Pass the flowers to the host, kiss kiss, take them back and head to the kitchen faucet. Put the flowers in the vase and put the vase on the table with the booze.
Bonus: a surprisingly lovely gesture—housewarming, birthday, new job—is to bring an orchid. It turns out that basic orchids are widely available and cost something like $25, including small vase. No room goes unimproved by an orchid.
It also turns out that orchids are surprisingly low maintenance: one ice cube at the base of the stem, weekly. Isn't that delightful?