Hiking in the Dolomites from Ortisei - help, please!

Ricks guidebooks tend to be selective and comprehensive. Much appreciated when I'm going to the selected places but not much help in others. Recommend you look at the Bartons
"Walking in Italy's Val Gardena" book. A Rick-like resource in useful detail we've used for a couple trips now. The Ortisei TI also has useful info and individual lift stations have some good maps of hiking possibilties. Your lodging may also have suggestions.

I also highly recommend the Barton's book. In addition to the book, I found much helpful information by searching Dolomites or Ortisei on this forum, including detailed responses from Laurel Barton. The Val Gardena card is worth it for most people. If I remember correctly, if you go on at least 3 lifts roundtrip, you will cover the cost of the card.

Would it be better to take the lift up from Ortisei and do a hike from there?

Absolutely. There are two lifts and a funicular in Ortisei so you have plenty of options for what hikes to do.

Here's another vote for Barton's book, we found it helpful. Maybe I'm an excessive planner but before our trip I used Google Earth to virtually "walk" the trails we were taking so we'd know what to expect to see. In addition to the book, when summer is closer take a look at the guided hikes offered on https://www.valgardena.it/en/summer-holidays-dolomites/val-gardena-active/ The summer hikes aren't listed yet but we went on two while we were in Ortisei. They are free if you're staying at a hotel participating in Val Gardena Active which most of them are.

We found the pass worth it. Not only did it pay for itself, but it was enjoyable to do a hike on one side of the valley, then later in the day take a free ride on the lift up the other side to the hut at the top just to have an Aperol spritz and enjoy the view.

My wife and I (in the same demographic, at 71 & 74) have stayed in both Castelrotto (3 nights) and Ortisei (4 nights) on two previous trips. We love the area enough that we are now booked for a whole week in Ortisei, arriving June 8- maybe we’ll run into one another. Your plan to travel to Castelrotto on the day of arrival is good, as long as you are there by mid afternoon. Castelrotto is a pretty town to wander around in, with some good views of the mountains, especially with the short hikes you mentioned. I would not use Castelrotto to access the Alpe di Siusi though, as you would have to take an additional bus to Compatsch or Siusi first. Instead, there is a lift right in Oriisei that takes you to the Alpe. On the other side of Ortisei are two lifts which take you directly to two other hiking areas. The Seceda lifts take you to the iconic Seceda ridgeline, which appears in every photo collection of the Dolomites. From the top station you can do a reasonably easy hike along the ridge and then return to the gondola, or spend a few hours hiking and take a bus back to Ortisei from Selva or Santa Christina.
The third lift from Ortisei is Resciesa funicular, which takes you to a plateau above the town, with fairly level hiking options leading to some spectacular views. If you plan on accessing all three options out of Ortisei, the three day Val Gardena card is definitely worth the investment. Even if you don’t want to do a lot of hiking, as John said you can just go up for the views and a leisurely spritz.

Thanks for the suggestions. I ordered the Barton's book, and it looks like it will be a valuable resource. We're planning on getting the Val Gardena card and are looking forward to wonderful stay in the Dolomites. If anyone has any additional suggestions, we'd love to hear them. I so appreciate the people who contribute to this forum!