how high up for new basement shower/toilet?

I'm thinking it would be nice to have a toilet and/or shower in my basement.
Either of these would need to be elevated higher than the current slab height so as to allow for a downward slope towards where I'd tie into existing drainpipe.
How high up do they need to be - is this basically determined by the length of the run of drain pipe?
Are there any 'low-height' traps for the shower or will the trap add another few inches that the shower must be elevated?
thanks!

You'd need 1/4"/foot to the waste line and vents run. Better to bite the bullet and break the floor for an underfloor connection. The shower drain trap would likely run 4-6" in depth plus the thickness of the new subfloor and the height drop it needs to reach the drain, plus the thickness of the shower floor pan which must also be sloped 1/4" per foot to the drain. The height is likely to be both cumbersome and may be problematic with your typical basement ceiling height. My unprofessional opinion.

floor

You would have to raise the floor at least 8" to allow the plumbing to be installed with minimal floor breaking. It would ALWAYS look like a "handyman" installation, assuming you have the headroof to do it.

HJ is right on... nothing quite like having friends and family come over and say "Oh, what a nice job you did on your bathroom".... Bustin concrete is tough work - but certainly within the realm of a determined DIYer (just finished bustin/plumbin/fillin a 3 X 5 hole in my own slab for a new bathroom..)

i figured y'all were gonna say that.
i'm not good at imagining what something's gonna look like, but --
i still wonder if an 8" step into the shower wouldn't be disguised by a lovely tiled curb. of course an elevated toilet is a different matter.
thanks folks.