Does anyone run 2 or more turntables...

I do. In my home system 2 turntables connected to 2 phono inputs that I have. It brings me
1. a convenience of playing records of variable speed without moving that belt over the spindle manually
2. secondary TT has 78rpm or single album setup (so figure different setup for different records. 78rpm setup can also be used for 12" single records.

In DJ application I used 4 Technics 1200:
First 2 for playback of single records
3rd For scratching
4th for LPs

Yes. Different tonearms and carts. Second one is set up and used for mono.

Drumarty,
I see that you've been a member since 2008. Haven't you noticed in that time that a number of members have 2 ,3 and sometimes more turntables? I'm sure that the reason is because they can afford it, and they want to exploit the strengths of one or the other for different types of music.
I'm sure they will tell you in this thread

Yes, if you have mono lps, you need a cartridge that is design for them. So, two tables.