why not just use any road bike or mountain bike?
if you are only going to go on day tours, you probably won't need four large panniers. you can probably get away with only two smaller ones.
my trek 1400 road bike is by no means a tourer. its a late 80's/early 90's racing bike. but i would still trust in on tour that lasted for even a few days, provided i didn't weigh it down to much with panniers filled to the brim. you could also try a comfort bike.