Adam,
I lived in San Francisco area for 3 years and my little sister has lived in Tahoe for ~10 so I’ve got a little experience that may be worth sharing. I’ve spent probably 20 days on the North end, and only driven the entire loop around the lake once to experience the South end. As Jerry said, the North side is much less developed then the South, I think mostly because the North is steeper terrain in general, while the South has a much larger flat section near the lake. The south side feels like a small city w/ large casinos and hotels, so if that’s your thing, head there. If you want smaller, quaint and cute stick to the North side. The long east and west sides mostly have little pockets of development, and day activity kinds of things.
Lake Tahoe is very bike friendly in general. I believe there is a paved trail that goes most (if not all?) the way around the lake. I know for certain it covers ~20 mi in the North area. The full trip around the lake is 75mi I believe, but can take 2+ hr to drive since a lot of the road is windy and slow (but has great views). There is PLENTY of hiking all around. I’ve personally hiked in the Tahoe Cross Country Ski Area just North of Dollar Point on the North side, on the PCT from Donner Pass to Tinker Knob as a quick overnight and in Northstar Ski Resort. All are beautiful areas! Also good to know, there is a public transportation system called TART (Tahoe Area REg Transit) that I believe is FREE and has buses going both directions around the lake. So its actually pretty easy to get yourself around once there, if you plan on staying close to the lake.
As for the “175 mi loop” around, I believe you’re referring to the Tahoe Rim Trail. It is a great trail that follows the PCT for portions on the West side of the lake. The lake is at ~6400′ and there are substantial mountains on all sides, so it is a fairly challenging trail. I’m planning to do this hopefully in about a year when I turn 40. But it would be a mistake to say the area is “only dahiking”. You could make as long or short a trip as you want since most of the day hikes would get you into Natl Forest, or even Wilderness area that you could then go as far as you want. There is a fair bit of water on the west side so you’re not limited to caching water. I believe the East & Northeast specifically are much dryer.
You mentioned beaches as well. There are some public beaches though I don’t know exactly where. The neighborhood my sister lives in has a private beach so that’s the only one I’ve been to. The water is generally COLD though… don’t think its like going to FL or SoCal :) I’ll second Emerald Bay as a beautiful area w/ some nice hiking. It’ll be crowded though.
Hope this helps!