They are not big inside (probably about the same as a 307 setate).... & when the wee one gets a bit bigger you'll be twatting it's heid off the door frame as you take it in and out of the back seat. (not on purpose).
We're currently changing our 5 series touring out for a VW touran.
Our 5 series is an awesome tool for transprting mucho sh*t at pace for 600 miles but 99% of our driving is short journeys.
Touran/Mazda 5/zafira/corolla verso are unfortunately & I hate to say it the answer. They are fecking huge inside compared to our 5 series (not so much the toyota), are smaller externally & they drive ok..... ish (but that's what you've got the S2 for...)
I'm just looking at it as a comfy van.
I think the sporty estates are on their way out. They're alright if you only want to run one car but if you need two anyway get one practical one & keep the plastic roller skate (wifes description of the elise) for fun.
Poxhaul do a VXR 230+ bhp zafira now I think.. (wouldn't have one myself cos it looks a bit chavtastic but as you've bought one of the only model of elise that Lotus chavved up as standard, might be right up your street.

Baggy