Thanks all for your thoughtful and helpful comments...now that I'm playing more often I can pay better attention. I find that several of my strings often become sharp after the guitar sitting for a day or two - not all, but I haven't really kept records.

Probably my bigger issue is string height - which I know is a trickier nut to crack...I realize I need to have a professional do it. I have to watch some videos on this - I'm willing to do the relatively "easier" parts of a setup - which seems to me to be most of it except taking the neck off...but I realize I need to make sure that the neck does not need to be taken off before I try the other things. I would only try this on my less expensive guitars but I need to watch some how-to videos first, including learning the sequence in which to check things, as well as what tools to acquire. Any tips or links to videos greatly appreciated.