Knowing the relative budget would help
I'm not sure a single portable device can do *all* of those things. At least nothing I've run across.
That said, knowing which features are 'must haves' could make the process easier too. Ballpark even- $300-400; 600-700, etc.
Personally, I believe you may be better off with a traditional receiver & speakers, since you can find very feature filled models on sale, and they can handle other types of music sources (CD, DVD, etc.). Some of the newer ones can also easily be added to a home network, and accommodate a simple iPod Touch, which would inherently give you a heck of a lot of streaming/app/internet music streaming/service options. Bottom line is that separate speakers/AV receiver nearly always sound better since you can physically separate the right and left speakers in a room to improve the sound (and locate them higher or lower to improve things).
If you weren't married to the idea of having a traditional stereo component for discs (etc.), and wanted mostly an [internet/network music based] streaming component that has halfway decent speakers built in, I would look at a basic Sonos Play3 system. It's ~ $299. See here:
Their wireless bridge would give you some additional flexiblity too.
I can give you more hardware options if you give more specifics on what types of music sources you need/want (e.g.pandora, CDs, iTunes library, youtube streaming, etc.).