SwissPass or Saver Day Pass. Only need one or two days. What are the restrictions for Saver Day?

Yes, you can buy the Saver Day Pass and it is valid for Mt Rigi. The validity area is more or less the same as the 3-Day Swiss Travel Pass, but there are some exceptions, mainly certain mountains (Schilthorn in Berner Oberland and Stanserhorn near Lucerne, for example) that offer free travel for tourists with the Swiss Travel Pass, but not for the Saver Day Passes (this has been a thorn in the side of some locals!). If you only plan to visit one mountain, Rigi, no problem. Otherwise, double check the validity map on the Saver Day Pass page: https://www.sbb.ch/en/travelcards-and-tickets/tickets-for-switzerland/1-day-travelpass/saver-day-pass.html
The other main difference is that the Swiss Travel Pass includes free/reduced admission to most museums in Switzerland. The Saver Day Pass is purely for transport. This may not make a difference to you though if you don't plan to visit museums.
And of course, make sure the Saver Day Pass is cheaper than point-to-point. For example, if you would just go Zug-Lucerne roundtrip for a day trip to walk around town, that is only 24 francs roundtrip with a normal train ticket :)

Btw - I know too many options can be confusing, but if the Saver Day Pass price goes up before you book and you want to hit more than one mountain, you could also have a look at the Tell Pass https://www.tellpass.ch/en/, a regional pass that is reasonably priced for 2 days travel (110chf in November). It's only valid in Central Switzerland but if you are staying within the area anyway, it's not a bad alternative. It covers Zug, Mt Rigi, Lucerne and a wide area around Lake Lucerne, including (unlike the Swiss Travel Pass) free access to Mt Titlis and, I believe, the gondolas at Mt Pilatus. You can buy it in advance or in Zug once you arrive.

Excellent information once again. So many options, so little time. Point to point might be cheaper, as you've suggested.
Unfortunately, it appears Mt Titlis is closed and Mt Pilatus has limited operations. Sincere Thanks!!

Ah rats, you are coming during a tough time of year with all the maintenance work.
Anyway you don't have too much time - Rigi and Lucerne, maybe the chocolatier, plus a spin around Zug (old town and the lakeside) can easily fit 2 full days. Just up to you whether you want to squeeze something more into it. Enjoy!! And fingers crossed you get some clear weather!

I think you have the suggested the best itinerary. Thank you!

Titlis would have been cold, and Rigi and Pilatus have similar views in many ways, so have no regrets about Pilatus / Titlis closures!