Days for sicily

How many ya got? Conventional wisdom seems to be a couple weeks, but it depends on what you wanted to see.

It depends on several factors: how much time you have, do you plan on renting a car or only doing public transportation, and what are your general interests? I spend two weeks last summer doing a road trip around all of Sicily and felt like that was just about the right amount of time for me. I picked up my rental car at the airport in Palermo and dropped it off there at the end of my circle around the island, spending my last few nights in Palermo. I would check out the RS Sicily book and read through the various chapters to see which areas interest you the most and make a plan from there.

Depends.
Sicily is not one place - you can’t stay in one town and day trip to anywhere on the whole island. It’s too big for that.

You could fly into Palermo and see it and something close by in 3-4 days. Or you could do a driving tour of 5 or more different stops across the island for a month. Or anything in between. So what on Sicily is your priority?

We have spent a total of five weeks on Sicily and haven't yet seen it all (we use public transportation). If you have less than two weeks, I wouldn't go that far.

Our interest is mostly in the historical parts, Roman, Greek, North African ruins. We also like museums. We are gearing up for Europe by walking 2-3 miles every day. So some hiking/outdoorsy stuff would be good. Answers so far have suggested that whatever time we choose to spend, we probably will want to spend more.

whatever time we choose to spend, we probably will want to spend more
That's the best answer I've ever heard for "how much time to spend!"

I spent 16 nights in just the East and South Eastern parts of Sicily: Taormina, Castelmola, Mt Etna, Siracusa/Ortigia, Ragusa with a few hours (only) in Noto and Modica, plus Caltagirone for wonderful ceramic shops and the tiled staircase, in and out of Catania. I've left the rest for a future trip.

as others have said it really depends on how much time you have, what interests you and if you will be driving or taking public transportation. i spent about a month last year traveling via public transportation. started in palermo then on to trapani, enna, siracusa, catania and messina. i did multiple day trips from each of these bases. Example: from siracusa i did 1 baroque town per day to ragusa, noto, scicli and modica. my interests are art and architecture so i didn't do beaches, nature (though i did go to vulcano), wine tours, or gastronomy. avoided taormina but went to places like randazzo, mazara del vallo and piazza armarina. missed salinunte, polizzi generosa and cefala diana due to the difficulty of finding convenient transportation to fit my schedule. i bet there are hundreds of other sites i don't even know about! all in all i felt i had enough time to see almost everything i wanted to at the pace i preferred. being there during the heat of may-june i enjoyed plenty of afternoon naps too! it was an amazing trip.

I spent 2 weeks in Sicily, mostly with a car. Planning was difficult because I had to choose carefully among the many options and there's a lot I didn't get to visit. I flew into Palermo, connecting through Rome, and out from Catania to central Italy for another week. Note that Catania airport gets shut down by Mt. Etna, not to say frequently, but it's not at all unusual. So if possible, start in Catania and fly out of Palermo, though Palermo is a smaller airport, so fewer flight options.