Deck 6 is a good deck - we've been in a deck 6 outside both times - the entertainment and facilities are on decks 4 and 5, decks 2 and 3 are bigger than deck 6 and so in comparison its quite peaceful - only a half deck cabin wise, and the decor is a bit brighter on deck 6. But that's not to diss decks 2 and 3, we had a late check-out cabin on Deck 2 the first year and although it wasn't as spruced up as Deck 6 there was nothing wrong with it and we think we will start going on Deck 2 or 3 from now on (just in case anyone thinks I'm dissing Decks 2/3!).
Actually its my hubby who has decided we only need Deck 2/3 from now on, personally I would prefer to be on Deck 6 or higher
Late sitting vs early sitting - late sitting is quieter, less children, and if you're like me and take an age to get ready, getting ready for 6.45 would mean going back to my cabin about 5pm which is still middle of the day in the Med, and can be awkward if you are doing a lot of full-day trips.
Having said that, its awkward to get to see the entertainment if you are on late sitting. Although they do repeat the shows for late sitters, and this year were making sure the first show emptied out before allowing people in for the second show, it was still difficult to get a seat if you didn't rush out from dinner to get your place. Also, if you didn't fancy the show in the Can-Can lounge, you would have no hope of getting a seat in the Oklahoma for the quizzes or whatever they were doing as people would get their seat after early sitting dinner and stay there all night.
Have a think about what you want from your days/evenings and that's the best way to work out whether to go for early/late sitting.
If you prefer your daytime activities (be it sunbathing or sightseeing) to nightime entertainment go for late-sitting as you have more time to come back to your cabin and get ready for 8.45.
If you prefer nighttime entertainment and want to watch the shows every night, have a seat for all the quizzes/karaoke etc. go for early sitting.
We weren't too fussed about seeing the shows so our evening would be a nice long dinner, a trip to the casino, a mosey around the show lounges, a trip back to the casino followed by a cup of tea and midnight snack in the Lido before bed so the late-sitting was better for us. Hope that helps!