This is your friend. Most airlines will first board their first class and business class passengers. They will also usually allow (tourist class) parents with small children to board ahead of the assembled masses. Yes it will be a long flight and you don't really want to add another 30 minutes in the seat waiting for the plane to fill up and take off in some circumstances, but other times you might.
For example, if you have a lot of carry-on luggage (maybe an umbrella-style folding stroller, eh?), getting on first gives you first shot at the limited overhead storage bins. This usually makes getting on first worth the trouble. We always take advantage of pre-boarding when offered.
If you are two parents, there is another method that might help (and thanks to Richard for suggesting this!). One parent boards as early as possible, carrying all the baby gear, folding stroller, tear gas canisters and six weeks supply of jar food, plus what the baby will eat. This parent's mission is to cram all that stuff into the overhead bins as early as possible, preferably before other passengers get their junk into the cabin. That parent then sits down and smiles smugly, having gotten stuff stored without having to drop the baby off in the galley.
Meanwhile, the other parent is out in the boarding lounge with the kids, who can run around or do whatever it is that won't be possible or easy in-flight (by which I mean “big potty” in the larger restrooms in the airport). This parent should also speak to the airline staff member helping board the plane, indicating that you'd like to be the last one to board. It is very important to mention this to the airline staff. The main reason is if the cabin attendants report an open seat, the airline might give your home for the next 14 hours away to a standby passenger, relegating you to a new life as a homeless person in say the Rome airport.
By the way, if given the choice between using an overhead bin in front of your seat, or behind your seat, always chose the one in front of you. Once everyone jumps up to deplane upon landing, trying to get something out of an overhead bin behind you requires you to quite literally move against the tide of people exiting.