2 days alone in Switzerland, flying into Zurich, meeting friends at the airport in Geneva

If you are hiking round Mt. Blanc that is in France, so the only chance you will have to see Switzerland is the 2 days between Zürich and Geneva.

My suggestion for Switzerland in 2 days.
Sunday 31st August: 1st night Luzern. You can get a train from Zürich airport to Luzern. Takes about 1 hour 10 minutes. 2 trains per hour, cost CHF 28.00 full fare 2nd class single.

Monday 1st September: Take a boat trip on lake Luzern (real name: Vierwaldstättersee). Then take a train to Interlaken via the Brünig pass railway. Journey takes 1 hour 50 minutes, but this is a scenic route. Cost CHF 31.00 full fare 2nd class single.

Tuesday 2nd September: If you had time I would suggest take a morning train higher in the Alps to Lauterbrunnen or Grindelwald, or even stay there instead of Interlaken, but if you have to be in Geneva "early morning" then this is not possible:
Early Morning train to Geneva airport. First train leaves Interlaken 05:21, arrive Geneva airport 08:37, then 2 trains per hour thereafter. Cost CHF 71.00 full fare 2nd class single.

Note there are at least one train per hour to and from any station in Switzerland. See www.sbb.ch for times and prices.

P.S. Switzerland is expensive, expect to pay over CHF 100 per night for an hotel. You just have to accept it.

If you are on a budget then consider airbnb for accommodations. As a single traveler you can find relatively inexpensive options. I just did a quick look at Lucerne for a single traveler and there were many options under $100 per night - mostly rooms in private homes for this price range. I have done this in various countries and it is a great experience!
You could also stay in youth hostels - despite the name people of all ages stay in them. I quickly checked the one in Lucern. Rooms for the dates you want range from 36 CHF for a shared room to 80 CHF for a private room - includes breakfast.Lucern Youth Hostel.
Good luck! Switzerland isn't cheap but you are only there for a few days - it's worth it!

If you wanted to just get to one place to stay two nights before you move on to Geneva I recommend staying in the Berner Oberland. You can stay in a place like Lauterbrunnen or one of the smaller towns up in the hills. Rick writes about this area a lot more in his Switzerland guidebook but in my opinion it is one of the best and most scenic areas in the Alps. You can watch his Switzerland episdoes on our website for free and that helps give a visual on each area. Once you have an idea built on what you may want to see and do you may want to look into some options for rail/public transport. Switzerland has a few options and usually they help save money for travelers. You can find more information on the Swiss Pass and the Swiss Card/s here.

The trouble with staying in Lauterbrunnen, or anywhere well into the Alps, on the second night is getting to Geneva airport "early morning". The first train in the morning out of Lauterbrunnen is 05:33 (ugh!), arrive "Genève-Aéroport" 09:07. Thereafter one train every 30 minutes. See sbb.ch for details.

I would suggest that after arrival in Zurich you head for Luzern and spend your first night there. Take it easy on your first day, have a walk around the old town, take a boat trip perhaps or go up the Rigi. For your second day I would suggest you follow the Golden Pass route over to Montreaux and perhaps stay in Lausanne. That would put you in easy reach of Geneva for the following morning.

If you do decide to take the Golden Pass Route, think about breaking your journey at Zweisimmen, there is a very nice station restaurant there.