I was able to successfully get into an circular (well, elliptical) orbit, followed by a (somewhat) successful de-orbit. I ended up going quite a bit higher than I had intended.
Went around about a whole orbit around the planet, Apogee at 325.063km, 1928.6 m/s, Perigee at 278.665 km, 2030.5 m/s.
That chart that Dark567 posted is really useful.
I had a rather large rocket. It has 9 solid fuel rockets, all attached around a core of 3 liquid fuel rockets, each with 2 fuel tanks on top of them, and attached to a 3-way split with an SAS on top of it. On top of that, is another single fuel rocket with another pair of fuel tanks on top of it. During launch, I have it set up so the solid and liquid fuel rockets all fire at the same time. I head (mostly) straight up, and that mostly is largely because with only one SAS it isn't particularly stable, but it's enough to keep it pointed in largely the right direction.
When the solid rockets run out of fuel, they're jettisoned, and then when the 3 main liquid rockets run out of fuel, they, and their fuel tanks, and the splitter, and the SAS are all jettisoned, and the final stage with it's liquid rocket and 2 fuel tanks gets fired up. I aimed at a bit of an angle up to the horizon, and fired that one until about 1 of it's fuel tanks was used up, and then cut the engine. Then I waited, and kept going up, until my vertical speed was around 0, which happened around 280km. At that point, I aimed the rocket directly horizontal in the direction i was going, and blasted the engine until I got up to around 2 km/s, and cut it (ended up around 2030m/s) (That chart that Dark567 posted is really useful.)
I still had about 2/3 of a tank of fuel left too. I had just waited for quite a while to do an orbit around the planet and record my apogee and perigee. Once I had done that, I fired the rest of my rocket opposite my direction of motion, and when it was dry, I jettisoned it with the fuel tanks. It was enough to slow me down, that I was able to drop down into the atmosphere and slow down the rest of a way, and deploy my parachute to a nice slow landing, that for some reason resulted in me exploding. Maybe landing in the middle of the ocean with no land in sight had something to do with that.
Or the 13.9G I had for a short while during my not-so-gentle re-entry.
And yeah, this game definitely needs a way to speed up time, all of that took about 70 minutes.
Edit: Hmm, seems the solid boosters don't particularly add a lot to that, I just took all of them off, and got into what should be a roughly circular orbit at around 125km with a bit over half a fuel tank left, and was then able to de-orbit and land safely. Testing with just the solid rockets on, gets me to 2500m, with a speed of 100m/s, so it does add some, and has quite a bit of thrust, but not much compared to what the liquid rockets can do for delta-V. Hmm, although with some testing, it is useful to getting a fuel-tank rich rocket off the ground.
And yeah, listing a mass for everything would be nice, how much an engine weighs, how much a fuel tank weighs, empty and full, etc. Would help to determine if it's better to just stack a bunch of fuel tanks, or use stages, with extra engines, so you can drop empty tanks.