I'm a non-driving mum who has done buses until I am blue in the face over the past six years, and these are my tips to consider:
If you haven't already done so, start scoping other people's pushchairs when out and about. Who can get off and on buses easily? Whose buggy gets wedged in the aisle on some of the single deckers, who has to beg the driver to let them on through the back doors (often to be met with a sneer and a foot on the accelerator...)
I agree totally about the folding thing, but for me width of buggy was critical for my local buses. Weight is a factor if you end up using trains (esp. overground) or the tube occasionally. You never notice all those steps leading over bridges and under platforms until you have a buggy with you...
And all those NCT meets - new friends in basement flats, trips to cafes...seriously, I dreaded one outing to Greenwich weekly because the friend seemed to live at the foot of the world's crumbliest, steepest, Georgian brick steps...
You might end up having a c-section which, initially at least, will affect your ability to manoeuvre a heavier buggy comfortably.
To be brutally honest being able to see my children was the least of my worries
- I was more concerned about them plunging Odessa Steps-style down some huge drop. I did not find the facing away thing a major problem - most light buggies have windows in the hoods now anyway.
If you really are going to spend lots of time on buses then think twice about space-hogging three-wheelers unless you want to be hated by lots of other passengers. Get a Maclaren Techno XT and put a sheepskin in it. This worked for dd and we never found a bus we couldn't sneak on to.
If you are going to walk lots more than get buses, then the better manoeuvrability of a good three-wheeler must be hard to beat I guess.
I did indeed use a sling for both of them (Baby Bjorn) until they were 8 months old - for any trips where a decent nap was not needed. And provided your back is up to it, they are excellent, esp. for cross-town trips.
HTH Welcome to Mumsnet :)