I believe the solution to much of the problem lies in Riak. It is erlang based, has Map Reduce, is document oriented, has Free Text Search built in, is Solr compatible (though sketchy on details there) and is very scalable, and importantly, operationally easy for a small team.

I too found an impedance mismatch with CouchDB for what I'm working on (which is much like a search engine, but not quite), and found Riak to be a good solution.