This is a tough question.
Even the fanciest of resorts will probably have very little for a non-diver to do and most of the guests will be out diving or sleeping. The Kungkungan Bay Resort (KBR) web site shows a swimming pool.
And nearby Bitung town is really only interesting if you like to study the palm oil industry.
There is the Tangkoko Nature Reserve nearby that is known for the little Tariser primate and birds.
Where I stayed was very basic. Food, shelter and diving. The divemaster and staff like to play guitar and sing at night.
Try
http://www.north-sulawesi.com/ to see what things can be done in the vicinity (river rafting etc)
as well as
http://www.divenorthsulawesi.com/
Write to the various resorts and get ideas from them about various day trips from Lembeh.
A lot can be seen snorkeling in the shallows at some dive sites.
July is peak season for Bunaken and Lembeh (mainly because of European summer vacations) so you should inquire about accommodation now if you want to go in July.
From California, the airfares are cheaper before March 31 and after mid-September. I just came back last week and was in Bunaken and Lembeh for the month of April, we had no rain in the daytime except on the way to the airport to leave. It did rain heavily one night. Water temps ran from 81 F (27 C) - 84 F. (29C)
Don't forget your international departure tax at Manado airport of 75,000 rupiah payable in cash after check-in (less than US$8) (different rate for domestic, and other airports)