Using my time wisely...

I don't know the travel time but you can use Via Michellin and get a rough estimate. It takes a bit of time once you arrive on the Spain side to walk across the air strip to Gibraltar. There isn't a lot to do once you are there IMO. You can go up the rock, see the apes and walk around the downtown area. If I had to do it again, I would skip Gibraltar and visit some of the white villages instead.

Thanks, Kathryn! Honestly, I just want to see the rock up close then back to Marbella. I have a number of pueblo blancos on my agenda by the way.

You are less than an hour to the rock. That said, skip the visit and admire the rock from afar. Spend your time on visiting the villages. Have you obtained and IDP for driving in Spain?

Thanks for the advice! I do indeed have my IDP.

My son wanted to go to Gibraltar so we added it into our plan. He really, really liked seeing the "apes" (he is 13). We went up a couple of times, once by cable car and back down, which was fine. Next time we took the taxi tour which I think was well worth it. We went to the Pillars of Hercules point, the St. Michael's cave which I thought was cool, to see the apes again (but not to the very top, pretty high though), and ended at the Great Siege tunnels. That took about 90 minutes or so. Third time we cable car up and walked a MILLION stairs down (I don't recommend that plan! My calves were burning for days!). We also went on a dolphin cruise, didn't see dolphin but did run across a humpback whale! We stayed 2 nights because I was traveling with a kid, a little overkill on it, but it was something he really wanted to do (seeing Africa across was a highlight for him!), and I'm glad we did it.

So, if it's something you want to do, then you should go, and a day trip is plenty -take the taxi tour, but if it's a crowded time, book it in advance. If you are kind of on the fence about it, it is skippable. But he really wanted to go and I think it was one of the highlights of the trip for him. :)

Oh and do find somewhere to park and walk across. When we arrived by taxi, I looked at the line of cars to get in and it was INSANE.

Thanks, Kim! More things to think about.