Hi Burt - and welcome!
You have come to the right place there are loads of very friendly people here to help and advise. Lots of memories to share too.
When it comes down to the theme parks it all comes down to a matter of personal preference, we all have our favourite parks and you will too.
You will see different opinions too, we all do things different ways, my ideas are not necessarily the same as everyone's.
As a first timer it can be a bit bewildering with all the Disney/Universal attractions. The first piece of advice would be not to try and cram too much in, if you rush around and try and see everything not only will you be exhausted but also it will not be nearly as much fun.
So pace yourself, do your research and have a great time.
Have you any children Burt? You will find that in a way you tailor your holiday to a child's needs, we certainly do these days and often end up just going on all the kiddie rides with our son.
As far as tickets go, it depends , the chances are you will become hooked and may visit Orlando again - we have been 13 times now - so the tickets you buy may be affected by this.
For Universal/Sea World I would suggest the 4 park Universal Flex ticket is a sound choice and gives you access to all parks for the duration of your stay, plus a water park too - WetnWild.
Disney is more complex with numerous types of ticket available, as with the Flex you can buy in the UK, however, if you are planning on going back in later years or just want a more comprehensive list of options the Disney 'MagicYourWay' is a good bet, with tickets that mean you can visit more than 1 park in a day and that never expire too.
see
www.mapleleaftickets.com as an example (where we buy our tickets).
Some theme parks are not as popular as others, Animal Kingdom for example will for many of us not merit a full day, whereas Magic Kingdom is one you may visits several times during your holiday - its is just a matter of how you enjoy each park.
I think generally MK is at the top of most people's list and I guess then it varies really - we have always liked Universal Studios, so apart from MK that is our favourite.
They are all totally different.
One of the main things to consider is the weather and crowds, whilst not wishing to make it sound like an assault course it can be difficult touring when the heat and crowds are at their highest - normally in the summer months.
Weatherwise April will be just about perfect, although if you are going at Easter time it is very busy then.
Either way , many people us including would always advise to plan plenty of rest time within your holiday, all part of the trying to take it all at a decent pace routine.
Anyway thats enough for now, could talk all day really.
Some useful links though:
www.attractionticketsdirect.co.uk
www.wdwinfo.com
www.disneyworld.disney.go.com/wdw/index
http://themeparks.universalstudios.com/orlando/website/index.php
http://disneyworld.disney.go.com/wdw/index