We had excellent service from Wren last year, the design service was WAY better than Howdens, Magnet or Wickes and everything came exactly when it was meant to, one replacement (incorrect) item was couriered out the next day, impeccable service. We used out own tradespeople though.
We love our boiling water tap, it's a Quooker with the pull out hose for flexibility. Quartz worktops are brilliant too, so glad we pushed the budget out a bit for both these. Also, we had a water softener put in which is brilliant if you are in a hard water area.
I am also really glad we didn't go for a pull out bin, having used them in holiday homes we weren't keen at all. We have a smart free standing one which opens by a sensor, you just wave your hand over it and the top slides open, much easier and far better use of space. We do have recycling in a cupboard but use our own container which is less restrictive in size than the pull out ones.
We have an Everhot range cooker, so all our heating comes from that, the kitchen is never cold. I much prefer it to eye level ovens and we so rarely use the microwave now we've kept it in the garage.
Yes to deep drawers instead of cupboards. We have knobs on ours, I'm not keen on the handle-less look but it's a matter of preference. If you do have knobs/handles, one central one is better than two as you can open it with one hand, but might restrict the width you can have, ours are max 90cm.
We've gone from 1.5 sinks to one big one, it is great having the bigger sink for washing larger things like fridge shelves and looks better too.
My main tip is not to rush the planning - we took 6 months over ours, had several designs done, went to showrooms repeatedly and tweaked endlessly. It was well worth it.