We always do DIY to Florida and Europe - we have 2 kids (ages 4 and 8) and we noticed that package companies often make quite big margins on top of the child flight seat price for the kids' accommodation , when many hotels either charge very little, or do not charge for them at all.
It would seem to me that the more people in your party (especially kids), the more likely that you would achieve savings DIY (especially if you are looking at villa/condo holidays)
We always price up both package and DIY options (not least to see how good a deal the DIY really is). From experience sometimes there is little to be saved if you are just two adults, between the two methods, but we have experienced 4 years now of saving up to £500 as a family - mainly due to this over-inflated kids' margin,and stayed at top class hotels which otherwise we would not have afforded.
We also generally like to hire a car on our holidays which fits in nicely with DIY ...no more hanging around the airport with a coach with a protracted journey to the hotel while everyone else gets dropped off first........then we make a point of beating the coaches back to the airport to check in before the crowds. Also the added advantage of doing your own excursions using the hire car at your own pace, on the day you want to, and without the rip-off prices.
Personally we see it as a plus not having a rep....I've never met one that was any use if we had a complaint, and besides which, we have recently had freinds that had a package holiday from hell....do you think their tour operators are forthcoming with compensation ? Hell No !
I'm not saying they are all the same but going with a package for reasons of having a fall guy if things go wrong is not high on my list.
To be fair you CAN get some bagain packages if you go last minute and are prepared to be flexible where you go, and where you stay (and I can appreciate that this does appeal to many people too) ...but I would rather have the exact holiday I want, and the enjoyment of the planning and looking forward to it.
Viva la DIY !!!