Would it be reasonable to do a day trip from Ennis out to one of the Aran Islands? I have no concept of distances and drive times. Looks like Doolin would be the ferry port, but not even sure if that's doable in November....? We'll be located in Tulla actually for the week, but methinks it might be more practical to spend a night in either Doolin or perhaps Glaway either before or after. Any thoughts?
Thanks much.

There are two issues here. Location and season.
I believe that the only ferry that operates in November and it leaves from Rossaveal, west of Galway City, to Inis Mór: that's about a two-hour drive from Ennis. There's a ferry that departs R. at 10.30 a.m. and a return ferry from IM at 5.00 p.m. So you'd need to leave Ennis by around 7.30 a.m. to be safe. You'd be driving back to Ennis in the dark by the way and probably some of your morning drive would be in the dark too.
In November, you can get weather that prevents ferries from operating. The trouble is that even if you phone that morning I doubt there'll be anyone there to check with before you leave at 7.30 a.m. So you might be making a wasted journey. Even if the weather's ok that morning, the ferry might have prevented the previous day's 5.00 p.m. departure from IM.
Overall, I'm far from convinced that it's a good idea anyway. Most people say that the great thing about the Aran Islands is their tranquility and timelessness, not something to be taken in over a few hours.
Ferry details.
I believe that the only ferry that operates in November and it leaves from Rossaveal
Ooops. For that read: I believe that the only ferry that operates in November leaves from Rossaveal.

I'm not all that sure that you could really hope to make it from Ennis to Rossaveal in two hours, either.

As far as i know, as mentioned above, Doolin ferries do not operate in November. Their website is www.doolinferries.com you can check it out there. It is possible to drive Ennis to Doolin in just over an hour...
Otherwise, Rosamhil is your only option. Ennis to Galway is about 1 hour, Galway to Rosamhil is about 90 minutes...