Headed to Crete in April for one week. Since this is the "low" season, I am attempting for the first time an itinerary that consists mainly of flying by the seat of my pants: fly into HER and spend the first two nights there (already booked) and on the third day decide if we want to stay in Heraklion or head out to another area and look for lodging when we decide to stop. Is that fine or would it be advisable to book everything in advance?

Also, can anyone recommend any decent flea markets or "antique markets" on the island?

Please and Thank You.

End of April/beg May is the Orthodox Easter, so some accommodation might be unavailable. Otherwise if not travelling at that time, I would expect it to be ok to wing it.

At this time of year you may want to concentrate on an urban experience combining Heraklion with Rethymnon and then Chania.
All three cities have Venetian era buildings and nearby sites like Knossos the Fortezza in Rethymnon and Ancient Aptera near Chania.

We have been able to find good hotels on a walk up basis in both Rethymnon and Chania. The benefit of dong a walk up is you can scout out the area and chose a hotel perfectly situated in the old towns.
Chania http://www.flickr.com/photos/stanbr5...7632117917828/
Rethymnon https://www.flickr.com/photos/stanbr...57654700502270
Heraklion https://www.flickr.com/photos/stanbr...57655935354556

I would find a place in Chania for a different experience from Heraklion.

What about markets?

We found antique shops walking around old town Chania.

Crete is huge and has thousands of hotels and pensions of every size, finding a place to stay if you play it by ear won't be difficult at all, regardless of Greek Easter...
Crete is not a traditional Easter destination for Greeks, and given the size of the island it won't be crowded.

Easter Sunday is this year on May 1st....

I am not aware of any flea markets or antique markets anywhere on Crete, although you can find single shops in any of the mentioned cities selling older objects ( i would not describe them as antique necessarily).

clausar, thank you for the helpful information. It was exactly what I was looking for.

Well, we got back on Friday. Our plan to not plan lodging ahead of time did not work as well as we had hoped. There was certainly no shortage of lodging available and the places we stayed at were nice enough but we could have found better places on booking.com. Next time we will book ahead.

The markets ended up not being an issue because we had enough fun just walking around Chania and Heraklion and exploring. Aside from Knossos, the stuff scattered around Chania, and the huge site at Gortyn we didn't do much archaeological stuff in Crete but it's hard to not end up seeing old stuff.

This is still low season for Crete, the problem with searching for accommodation on the spot, is that you can rely only on what you see, while there may be many good hotels and pensions nearby..... that are not easy to find..
What i usually did, was using the app of booking.com and display everything that was nearby.. this has always worked for me, especially in the shoulder season, when hotels begin to have limited availability. ( i try to avoid the high season).

I hear ya but one would think that the "good" places would be open year-round, or at least a month on each side of the high season. The hotels we found were really nice -- they just were not what we would have preferred to stay in.

Sparkchaser, what may somewhat affect what places are open is when does Easter Fall ... when Orthodox Easter is in March, it prods places to begin the opening process sooner. This year it's the latest in Memory, May 1.

Crete is not an Easter destination for Greeks, unlike Corfu or Mykonos (just to give you some examples).

Hotels in Crete open and close based on the scheduled charter flights that land in the nearby airports.
Crete has the longest season in Greece, which starts at the end of March for Heraklion and 2 weeks later for Chania.

Most hotels are not open year round, with the exception of the bigger cities, that have traffic from business travelers.