I used to live in Geneva, and while I understand that it's probably not worth a chapter in a Steves' book, there are still things to do there. Also, there is cheap accommodation at www.cityhostel.ch which is about 3 blocks from the train station.
I'll just tell you what I'd do in your situation.
Arrive Geneva, and just before you exit the baggage area, pick up the free 80 min transportation ticket from the machine. Then you can take either the #10 bus on your left as you exit the airport, or go down into the underground mall (further left) and catch the train. Both take you to the main train station, Cornavin. I'd book one night at City Hostel so you can undo some jet lag and see a bit of the city.
If the weather is good you can take a free bus (included in your hostel/hotel stay) over to Calvin's Church and climb the bell tower, rent free bikes (www.geneveroule.ch), visit CERN. Not great weather you can go to the Red Cross Museum or go shopping in the underground mall near the train station. (Left out the main entrance, cross one street, look across the other to see the McDonalds, enter it and go thru it and you are at the top level of the mall.)
Book train tickets to Lauterbrunnen which is about 3.5 hr trip. You can get inexpensive rooms there at Valley Hostel, or if you want REALLY cheap, bring your own pup tent and stay at www.campingjungfrau.swiss . If you buy your own food at the local stores, you can save a lot.
There's easily enough stuff to do in the area to keep you busy for 10 days, assuming you like walks with fantastic vistas.
Also, I wouldn't rent a car since it will just sit idle in the Lauterbrunnen/Murren area.
I'll send you a site with our dozen favorite hikes with maps and pics. Just click on your name in upper right to read your forum mail.
Consider buying a Berner Oberland Pass
https://www.regionalpass-berneroberland.ch/en/pass-and-infos/area-of-validity/
if you love using their cable cars and mountain trains, or a half fare card ($130) is another option.
You could also make a side trip or stay in Lucerne for a couple of days.