I usually drive with my dip beams on all the time.
Unlike fogs they're aimed properly so dont cause glare, or annoy other road users, and can only improve your visibility to others which reduces the chance that someone pulls out on you or cuts you up because they "didnt see you".
I share the sentiments above though about folk driving with front fogs. Especially the knobs who drive around at night with the front fogs and sidelights on, but dip beam off!
If you wanted to wire them in without using a seperate switch, then you could connect them to your Main Beam wires. I believe that would be perfectly legal, as you only ever use the main beam when theres no oncoming traffic and theres a nice blue indicator on the dash telling you there on.