It's helpful to think of this process in its segments:
Server/database
Control Point/GUI
Renderer/Player
Then it's helpful to understand the differing capabilities of each, and the different protocols each segment can handle, and the role they play in the process. Given this and your situation above Airplay will be your only option if you wish synced wireless playback. I've encouraged and tested 'Soundseeder' for Android, but it is still clumsy to sync 2, let alone more wireless speakers using it. Airplay, however, *CAN* play back synced audio, but I've found in my own testing that not all Airplay devices are created equal: 3 Pioneer wireless Airplay speakers sync perfectly; add a few non-Pioneer Airplay compliant devices, and they're off by 500 millisesonds or more-right back to fiddling like Soundseeder. Therefore, if you desire TRULY synced playback, your options narrow, in my experience, to sticking with one brand of device for renderer/player (like I did with Pioneer, or others with Sonos). Presently, I'm testing the following:
Server/db: Subsonic, Plex, minidlna,Twonky
Control Point/Gui (I'm all in on Android) Nexus 5, Nexus 7, Samsung GS3, and have settled with 2 different GUI's: BubbleUPnP (DLNA) runs on server machine (transcoding and WAN server like Subsonic) along with Sub,Plex,Mini, and BubbleUPnP client runs on Android, and accesses all the servers above, and sends to my renderers usng DLNA. Since all Android devices are rooted, I also run AirStream (paid Airplay compatible broadcast app) to play back synced throughout my flat. My Pioneer speakers support both DLNA and Airplay protocols and sound impressive after a bit of equalisation to mellow down the bass.
Now...the handoff of sending duties is another matter (concern about battery life of control point,etc.) and will also vary, considering who is actually doing the work. For example, I can use either protocol and begin streaming KEXP, but if I want Airplay sync, it relies on the Android phone/tablet (I'll never own anything Apple) for sending duties. Same with DLNA..Bubble remains running in background to stream, but of course unlike Apple Airplay, I can simultaneously use the device for many other tasks*. However, the Pioneer also comes with it's own poor Control App, and I can start the same KEXP stream from my Androids, but then turn them off, and the stream continues. Further testing has competed with other projects, so I can't say what happens with on-the-fly playlisting behaviour in both protocols (but I might imagine similar to above), so I would think prepared playlists would be your best bet, until other solutions evolve. In the interim, I use my TYLT wireless charging dock to rest my Nexus 5 and it remains charging(ed) at home at all times.
*as an early Chromecast adopter, I also use apps (Plex, BeyondPod,etc.) with Chromecast-ability, and CC takes on the workload, unless 'Tab' streaming, and I've been told Apple Airplay dedicates the device to Airplay only (like mirroring/Miracast) when in use, but since I don't own any Apple stuff myself, I just go by what I'm told on that..ymmv.
