You have to hike to Scout's Overlook to start the Angel's Landing Hike. I'm in my early 60s and did fine with plenty of stopping to rest and rehydrate. Very easy going down though ;) I won't attempt Angel's Landing so Scout's Overlook is as far as I go. As sharondi says, the Zion Canyon Overlook Trail that start at the east end of the tunnel is short and easy with a big payoff at the end. never done the Observation Point hike so I can't speak to that. Igott's suggestions for Zion are good.

I Bryce, Navajo/Queen's Garden is a classic. Peekaboo is also great. We did the Fairyland Loop and loved it but it is a longer hike...8 miles so 4-5 hours...start early to avoid afternoon heat. https://www.nps.gov/brca/planyourvis...rylandloop.htm

Bring more water than you think you need. You may meet people that need it along the way. I don't suggest hiling in Bryce the first day you arrive until you know how the altitude is affecting everyone in your party. Most people aren't bothered but some have a very hard time with it...don't rush.

I love Zion! I would spend more time in zion (2-3days) and a day in bryce. Observation point hike was a little more strenuous at the beginning of the hike because of the incline and gets easier( mostly flat) as you reach the viewpoint. Personally, the views are more spectacular in observation point than the more popular angels landing but there's more thrill with the hike to the top of angels landing. Both hikes are rewarding.

Thanks again for all your suggestions! If you think of anything else please write in! I will continue to check back here!