Hmmm, interesting thread as I do like my toys but let's see if I need them...
Electric memory seats - Mrs Bing drives the car rarely, but I do like to be able to adjust my driving position on long journeys, which I do a fair few of
Heated seats - no brainer in a roadster, as is
Wind deflector 
, though I guess not essential
PDC - very useful, as I reverse park all the time now to negate my natural incompetence... And of course for the rare ocassions when Mrs Bing drives
Satnav - I use a fair bit as I travel a to new customer sites, or on roads from hell like the M25 where I may need to divert. When I get round to integrating my iPod it will be very useful. Oh, and Mrs Bing can't find her way anywhere outside routes she's travelled at least 100 times
- all that said, I used a Garmin in my last car which was fine, just kept forgetting to re-charge it
CD multichanger - yep, used whenever the radio's rubbish, currently loaded with Adamski Beats :wink: ; that said if you have all your music on an MP3 player (I don't, yet) then not essential if you have an iPod aux
Auto wipers and lights - lazy, but also just sensible in my view - and I am a believer that there's some things a car should just do for you other than spend your money
Bluetooth - can't live without because of work, though the mic is not very well placed for shorties... Agree it should be standard (safety feature) in all new cars
MSFW - used for controlling phone, and stereo volume etc whilst motorway driving, could live without the paddles but they are fun
If you use the car a lot, especially on long / busy journeys or commutes, I think a basic spec has to be anything that stops you buggering about and being distracted because it's safer for you and everyone else - so Bluetooth, auto wipers / lights, electric seats, MFSW etc.
Things I wish I had :
Xenons - for seeing, as said above, though brighter bulbs may well be fine
Cruise - THE one thing I really want, which fortunately I'll be able to do when I have some readies
Hard top - but then the e89 has one of them ; for mine I considered buying Tikamaks, but really couldn't justify it
Cup holders - not essential
That's me though - I can find a justification for most toys that I want that I can afford (after all I am typing this on a iPad that I still haven't found a properly legitimate reason to own after having it 9 months). I am currently trying to work out why I should have an M, and where I am going to steal the money for it from :evil: Seriously though, perhaps it depends on what you can afford to have ?
I think the biggest 'downgrade' that you'll have an issue with will probably be the power of the new car - but then there might not be much in it as I haven't driven a 23i.
Sorry - bit of a ramble from me back at you Steve, hopefully not entirely useless
However it would appear most of my toys are justified, for me :yeah: