Dolomites Itinerary- suggestions, changes, etc

I haven't spent any significant time in the areas you're asking about, so I can't give you any personal advice, but I did want to drop a link here with a YouTube blog I recently found that covers some of your locations:

Their YouTube channel is the Adventures of A+K and they have videos documenting their 2019 trip to Italy (including hiking the Dolomites). Here's a link to all of their Italy videos if that's helpful:

https://www.youtube.com/playlist?list=PLZKRTK1yCEM4CYsp5qfHZKI9m5aKqwMye

We'll be in Italy over the summer and are heavily considering taking the cable car to Seceda too!

You are trying to go all around the Dolomites with only 3 nights. It is tricky. Coming from Venice, I would probably aim for Cortina d'Ampezzo as a single base. There, you can take the Tofana cable car as a "substitute" for Seceda. Lago di Braies is within driving distance, and the Drei Zinnen area has many beautiful hikes, though more research would be needed to determine which ones are "baby-carrier-friendly" (I think that starting from Rif. Auronzo, you would have a few options).
You could then drive from Cortina to Sirmione via Arabba and Carezza to enjoy the scenic mountain passes.

Really appreciate the input. I kinda had my heart set on staying in Val Gardena area but totally can see how Cortina is more convenient. Definitely some things to think on. I don’t have my heart set on Lago do Braes so trying to determine if cutting that makes sense.

Also we are baby free on this trip so we have a lot more options!!!

I misread the bit about your baby ;)
If you're not set on Lago di Braies, then you could also stay in the Val Gardena the whole time. It would make sense too! Hard for me to say which part is better, but Cortina is more Italian, and Italian speaking, whereas Val Gardena feels Tirolean and speaks German or Ladin before Italian.

Thanks so much! That definitely makes sense. My Italian is barely passable and my German is basically restricted to “prost”. My great grandmother was tyrolean (spelling?) which drew me to that area! There are so many places to visit in this area that these few days are barely gonna touch the cusp!

I had this idea of skipping Lake Garda and instead adding two nights in Cortina (going there from Venice) then head to Ortisei. Does splitting that up like that make sense?

We love the Val Gardena and having visited Lake Garda, I would not trade the mountains for the lake in any situation. Spend your extra nights in Ortisei. It is truly lovely in September. (We go there every September.)

Additional hikes to consider:

• Rasciesa (short or long options)

• Ciampinoi to Passo Sella with a return hike or return to town by bus from the pass

• Col Raiser has many options. You can walk from Seceda to Col Raiser if you like and return via S. Cristina.

"Hike around the Alpe di Siusi" leaves you many options.

1. It is a longish day trip from Ortisei but the best hike up there is, to us, from Panorama to Zallinger. This necessitates taking a bus to and from the Alpe di Siusi Lift but is well worth it.
2. Another AdS option, from Ortisei, is hiking from the top of the lift there to Saltria. You can hike back or take a bus to Compatsch, the gondola down, and a bus back to Ortisei.
3. There are shorter options, as well just doing a loop from Mont Seuc.