We were given a
mamaRoo as a present. My (2 month old) son loves it, but I don't think it has anything to do with the fancy motion system the seat is known for. He just loves staring at the mobile, and maybe finds the seat comfy, who knows. [Side note: I accidentally snapped a piece of the frame while assembling it, but we called them and said it broke during assembly and they said, no problem, we're sending you a new piece, with a return shipping label. Please send us the broken piece so our engineers can analyze it. How's that for CS!]
We also borrowed an ancient Graco swing from my aunt (it was originally a wind up but she also gave us a replacement head unit that was electric) for where he is babysat. The babysitter attached some toys at the top and instead of staring straight ahead my son tilts his head way back and stares up at them the whole time. I'm starting to think we should have just gone with a cheap seat that has a nice mobile. Thankfully we didn't actually pay for any of this stuff, so I don't mind.
Back on topic, as far as 2 in 1's, Fisher Price makes two swing/seat combos,
here and
here (there are other designs of each). Graco has one too, the
Duo. Can't vouch for an of them, almost everyone I know has some version of the bigger spread-legged Fisher Price swing.