MacBook v iMac when already own iPad

I own an iPad and an iPhone and have a laptop which is about to die and i want to replace it with an apple product. I have £1000 and considering either an iMac or a MacBook pro. I am not desperate for portability since i have the ipad, however it is always useful.

I just need the computer for when I need a more powerful device and complex issues that the iPad can't deal with. I do 2-3 day trips quite often and am planning on doing some traveling in the next year. The MacBook are nice for the portability, however the iMac are nice for the big display.

On a side note, do people who own both a MacBook and iPad take both when traveling?