Like RW I stay in Kilifi when in Kenya and find it to be a charming typical Kenyan town, no beach boys and as the Kemri Research Programme is based in Kilifi Hospital the locals are used to Mzungus being around so they will greet you warmly but no hassle or trying to sell you things.
Bofa Beach is beautiful, again the only people you will see are the local fishermen, my grand-daughter had a great time snorkelling in the shallow waters last October.
There are some villas for rent along the beach or on the creek.
There is a company which do villa rentals Kilifi Konnection, the lady who runs it lives in the area so you are dealing with someone with local knowledge.
There are local Dhow Cruises and for the children (depending on their ages) an excellent water sports centre 3 Degrees South who are based in Kilifi Boatyard.