What tires do you recommend for the Twenty? I'm still riding the originals on mine. Did you swap out the front rim, or the whole wheel?
Schwalbe Marathons come in a 20 inch size although you cannot run them at their max pressure on the stock rims... at 65-70 psi they ride pretty nicely and this is within their operational range.
Am using some BMX tyres that I had at hand which are for urban riding so they have a nice roll out and ride quality and again, am running them at a slightly lower psi to balance the ride quality with speed.
Swapped out the front wheel as I had a spare that is spaced at 95mm to fit a Raleigh fork... if one does nothing else to a Raleigh Twenty, changing the front wheel to alloy and adding better brake pads is the best thing you can do to improve stopping.
Will eventually lace new rims on to the hubs... CR18 rims are a good choice for this as they have a nice vintage look and are very well made.