I'd Like to build a family coaster but I'm not sure about a family coaster's specs. Can you give me some pointers?

Well it depends what kind of family coaster you plan on making, as they can vary wildly in stats and intensity. There are the smaller family coasters like Vekoma suspended coasters, but coasters as large as Verbolten or Cheetah Hunt are generally still considered to be family coasters. A good general rule of thumb for most coaster types would be to have the coaster under a 50-60 ft (15-18m) height max and to stay around a 40 mph (65 kmh) maximum speed. G's shouldnt go over 2.5 - 3G's at most.

Ok thanks Rudy. That helps a little bit. I guess the other question I have is given that height restriction family coasters don't usually have inversions right?

Not usually but Cheetah Hunt has one but it is the only noteable family coaster that does. The family coaster I have the most amazing experience with is Fire Chaser Express which has a 72 foot lift but is on the side of the mountain and silt works it way back down with its max speed of 34mph and a max drop of 30ft.

I'd consider the Rock N' Roller Coaster to be a family coaster and it has three inversions within its layout, so it all depends on how you make it work. Obviously no seventy foot tall vertical loops would work, but smaller inversions can.

Firechaser express might be a little too complicated to recreate in RCT3 do to the backwards launch

But it is still an example of what family Coasters are like

Everyone definitely has good points.