+1 for Dapper - I'm a big fan. It is very fast and we use it to serve our live (mostly read-only) traffic, while using something like Entity Framework for the backend Administrative UI, which has a lot of inserts and updates.
I wrote a Dapper extension for working with SQL Server's geospatial queries and types a couple of years ago - have they added anything like that yet? Otherwise I'd be happy to add it.