L293D vs ULN2003
Please treat this as a provisional response Darren. I'm interested in people's answers to this too as I'm likely to be doing the same fairly soon.
I'd say that if you're able to provide the detailed control sequences in software, then using a L293D sounds good to me. With an H-bridge you can choose to pass current through a coil in either direction which is necessary for stepper control, but I don't think this is possible with a 2003 as they are meant to switch the low-side of a circuit (coil, lamp etc) assuming the other end is connected to the supply. I hope I got this right.
There is a current limit on a 2003 is 500mA but you can connect several inputs and outputs together to overcome the limitation so you could drive a 800mA solenoid this way.