Two that I greatly look forward to are, flyby of Pluto, and ExoMars mission to search for life on Mars:
2015 New Horizons flyby of Pluto, and its 5 known moons (it may well discover more). Moons of Pluto
Pluto should still have a thin atmosphere (which forms briefly when it is closer to the sun)
And - it is similar in size to Triton. It's not impossible that it might be as active and interesting as Triton, which also has nitrogen geysers, Pluto might be active also. Possibly some of its moons too.
Then there is the ExoMars - first technological demo in 2016. First mission to Mars in 2018. It is the first mission sent to Mars with the capability to detect life since Viking in the 1970s (Curiosity can't detect life unless really obvious, which it probably won't be on Mars).
Lunar missions surely. This really interesting kickstarter could drill down 20 meters, up to 100 meters into the lunar polar ice. Backed by the likes of Brian Cox and many scientists in the UK.
It' got over 40% funded on its second day - and is now fully funded. This is for the initial stages - which would then lead on to the mission itself later on.
We may well get more crowd funding space missions also.
Also expect missions to Jupiter's moon Europa in that timeframe - the ESA JUICE is due for launch in 2022, arrive at Jupiter 2030.
But the first two, they are at an advanced stage.
New Horizons on its way, and woke up from its hibernation successfully - sure to happen apart from accidents (hopefully low probability).
ExoMars - well they are doing a careful approach with a technology demo, lots of telemetry. If there is an issue with the technology demo in 2016 it might get delayed. But I expect it to happen some time soonish.
It will also be really interesting to follow up Rosetta updates - as the comet beomes active as it comese in close around the Sun - and quite likely Philae will wake up some time next spring. If so - then its cold position shielded from the sun might be an asset, let us observe what's happening close up on the surface of the comet maybe right through to perihelion.
In your 10 to 20 years time frame also, it might get a lot easier to launch to space. Maybe even fly directly into space as with Skylon.
So- easier to be surer about the next 5 years, is a lot to look forward to and be excited about in that shorter time-frame also.