It will be great :-)
Medication - take all essential items like this in your hand luggage, just in case your suitcases were to be delayed or lost. Probably best to keep them in original packets and bring the dispenser empty. Check the rules on what you can take as hand luggage. For example there are strict rules about liquids which also cover face cream / suncream etc.
It's a good idea to pack a few essentials for everyone in hand luggage eg clean undies and a T shirt plus a swimming cossie, just in case of delays with luggage.
Flying - do online check in beforehand if that's offered by your airline. Get to the airport in plenty time - better to be early than miss you flight due to bad traffic.
Hotel - check what the hotel provides for you, for example most all inclusive hotels provide towels for the beach / pool as well as your room. You just collect a clean towel everyday.
Lists - I love lists as it helps me feel in control! Start lists of things to pack, things to take in your hand luggage and maybe things to do before you go (empty fridge, empty bins, lock windows etc). You can add to these as you think of things and just tick items off as you go. Essentials are passports, tickets, money and medicine. Everything else you can buy on holiday if necessary.
Packing - depending on ages of your family make everyone responsible for packing their own stuff, so it doesn't all fall to you. Even little kids can chose their favourite toys or T shirts and you can just tick off your list to check you've got everything.
Suncream - nearly always cheapest to buy before you go. Look out for 3 for 2 offers etc. start with higher factors than you would at home as your holiday can be spoilt if anyone gets sunburn.
Ground rules - again depending on ages of your kids agree appropriate rules in advance. Eg for little kids, no ones goes in the pool without a parent. For teenagers - what are your views on drinking, bedtimes etc.
Relax and have fun :-)