I have 2 mountain bikes, an old raleigh that I have had for over 20 years and a new co-op 2.1

I am looking for a high quality road bike. One that I can use for speed and endurance. 

I want to go fast and long but I don't want to spend too much ($1000-$2000).

Any suggestions?

Also what is the best way to build leg size, road riding with a mountain bike or or road riding with a road bike?

I look forward to an experienced persons advice.