Anyone been to thessaloniki in Greece

Going there in a few weeks time for 10 days and then I am going to Bitola in Macedonia for a short stay. Anyone been to these places and would they recommend any nice things to do and see.  Never been to either places before.

With regards to going to Greece would you need to be extra careful due to the fact its going to be well known tourists are going to carrying a lot of cash. I wouldn't care too much about being mugged if someone needed the money more than me but I don't want to get mugged if my family are with me.

Thanks in advance.