Borghese Museum and Gardens & Spanish Steps area

That seems reasonable. I don't know where your hotel is, but we did something of the same in reverse last year. We stayed near Plaza Navonna and took a cab for an 11:00 time at the Borghese. We got there plenty early to enjoy the gardens, and after our allotted 2 hours, we walked through Plaza del Popolo, down via del Corso, stopping for lunch at an outdoor cafe, then to the Spanish Steps and back to our hotel. You could plot out a route on Google Maps and see if it makes sense to you. The Borghese Gallery is well worth the visit.

Then could one eat lunch and walk to Borghese museum and request a time block in afternoon?

Do you mean just get tickets that same day? Often the Galleria is sold out in advance, so make a reservation as soon as you can. They take reservations for 9:00, 11:00, 13:00, 15:00, 17:00.

Do get those reservations in as soon as they are released for sale. They go quickly, and when they are gone they are gone.

You can't just rock up and hope to get in.

You need to be there 20 to 30 minutes ahead. If you don't pick up your tickets on time you can't go in. Be prepared to put your big stuff and cameras in a plastic bag.

Be prepared to put your big stuff and cameras in a plastic bag.

Just to note that some of the information on booking site for the Borghese is out of date. It states that you must check cameras but non-flash photography has been allowed in state museums since mid-2014. Pretty much everything else must be checked, though, and the bag is provided for a few small, important items - like a ladies wallet and passports - you wish to keep with you.

And Nigel is spot on, advance reservations are a MUST. Make yours as soon as possible as they sell out quickly during high/shoulder seasons.

http://www.tosc.it/tickets.htm?affiliate=T2C&sort_by=event_datum&sort_direction=asc&fun=erdetail&doc=erdetaila&erid=912678&language=en

Don't miss the Boeghese.
The Spanish Steps will take you 15 minutes, maybe 30.

Do get tickets in advance. You might even consider a guide, that way the tickets are taken care of and you likely get in directly rather than waiting in the long line. Pus, the guide can tell you the stories of the exhibits. In fact, if you haven't seen Rome, consider a guide for Monday. Talk to them and tell them what you want to see in that day. They will take it from there. It is a very good way to maximize your experience when time is short.

Thanks for the detailed information on my original question.

Would you recommend renting a bike to see the gardens area at Borghese? It seems you could leave a driver's license as an ID in renting?

Actually I think the Spanish steps is 5 minutes. Just a bunch of steps from one street level to another. Other than the surrounding buildings there is not much to view.

How far in advance are tickets available?

Do get tickets in advance. You might even consider a guide, that way
the tickets are taken care of and you likely get in directly rather
than waiting in the long line.

The line at the Borghese isn't as nearly long as at some other attractions as everyone must have a reservation, and they only allow 350 or so in for every reserved two-hour time slot: excellent crowd control. You are required to be there 30 minutes before your slot to check belongings not allowed inside the museum. I recommend being there earlier than that should the checkroom be busy. Everyone enters 'directly" whether with a guide or not.

Patricia, tickets are currently available through September so it looks to be about 6 months in advance. It's very easy to check though: just click on the link I provided above, and then the dropdown for the month you want. If that month doesn't show, they're not available yet.

You can rent bikes in the park, but it's easy to walk as well, or you could take the silly little train that runs through it.

That plastic bag is quite durable, I still have mine. I put a wallet, keys, meds (inhaler), camera, and a bottle of water in it.