Which Board for a newbie.

Im looking to get involved with Arduino and am wondering what board to go for.

Im been working in electronics for over 30 years, done my City & Guilds qualification and have been self employed for 27 years, Im currently getting involved in 'Smart Homes' which lead me to this site and the awareness of Arduino.

I don't want to get a starter pack as I have most of the components, just looking for a suitable board that has plenty of flexibility without the need to upgrade too soon.

A project Id like to start with is an automatic stair lights that once I've experimented with the various options using Arduino hookup I will make a single dedicated board for the product.

Personally I'd go for one of the more practical sized boards like a mega2560. Get yourself a handful of the ATtiny chips. You can then use the mega for your development. And once you have something ready to go, just burn an ATtiny to do the job, and move on to the next part of the project. This way you can have distributed intelligence in your system.