I love parties at home.
Consider how people will move through the rooms, and help that flow. You want people to circulate so have a drinks table far from a desert table etc.
I find it is better to keep it simple - cut down on choice but increase quality.
Have plenty of places for people to set down empty plates, napkins, glasses etc. Ditto, arrange enough seating, some of it a "quiet corner."
Hire a few teens to "manage" the floor on the night - remove the dirty plates and glasses, run the dishwasher, replace ice, etc. Keep the place from looking increasingly ragged. This will be the best money spent. Have a simple, clear set of expectations. Do a run through the day before with them. They will have a hoot and you can really enjoy yourself. You will be very thankful the next day!
A large floral display or two really gives a lot. I do my mum's trick - a lot of long stem greens with one or two blooms. Inexpensive but stunning. However at this time of year you have the added benifit of Christmas and all that cheer!
A fun but lovely addition are naice bowls of colourful sweets - smarties/licorice allsorts, oranges with cloves in the skin smell divine, a pyramid of shiny red apples looks beautiful.
Have a lovely time op and happy birthday. Will you come back and tell us how it went?