What about a rowan? That would look good and not cause too much dense
shade for the flats plus it will have berries on it.
I have just borrowed a book from the library which was so good I have
ordered it from Amazon called TREES FOR THE GARDEN
It has loads of suggestions for trees for various situations and has
unusual as well as common varieties.

Borrow a copy from the library.

If it's in a village situation can you not ask for suggestions from
Groups of local clubs or schools, that way people will feel involved and
will tend to look after 'their' tree.
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk