For me, a laptop is something you use when you can't get to your desktop. So how often can you not get to your desktop? Often: get a laptop. Infrequently: Get a second desktop.

Alternately, buy a laptop (and possibly a docking station) and plug in an external fullsized keyboard, monitor and mouse. Of course, then you've just turned your laptop into an overpriced low-end desktop. But that gives you the capability to un-dock the laptop and take it with you when you need to be mobile.