I think for your usage a 14" regular or wide will be perfect.
12" laptops have a very crammed keyboard IMO. Some keys are narrower than others and it pisses me off but thats just me. Generally Ive found that 13-14" machines have comfortable keyboards. Unfortunately, I believe the only HP and Sony have 13" laptops and I dont recommend either of those brands. Hence look for a 14" with the best specs you can get with your budget. Im pretty sure Dell has em, as does Acer and ASUS. Fujitsu and IBM are a little more on the expensive end.
Also, look into how much heat the machine you chose produces. My Acer is a beast power wise and a pleasure to use but it does heatup to the point where its not comfortable to have it sitting on my lap for extended periods.