MoFo
The Embraer 170/175/190/195 family, fondly refered to as The Jungle Jet is designed for 70 to 110 pax. At the high end similar to a 717 but much lighter!
The 146s as configured by NJS carry 64/76/87 at 2+3 seating plus a few business seats. I think European operators of the 146 get up to 115 into a 146-300/RJ100 using 3+3 seating.
I think the 717 is too heavy and large to be considered the RJ replacement.