The CBR250 and Ninja 250 make great starter bikes. They are easy to ride and cheap to aquire, especially if you find one that has already been tipped.
That being said, they leave alot to be asked for on the power front.
Jesda, for you I would look at something a little more on the touring front. Either an enduro, or an adventure. The 250s are light, and great on smooth asphault, but get super gittery on cracked and rough roads. They are also very small, which will make them uncomfortable for somone of your stature. Also the seating position leaves a lot to be desired when you want to sight see.
I suggest looking at maybe a Suzuki V-strom 650. They use a 649cc 90 degree V twin. The riding position is very upright, and designed for touring while also being very fun to ride around corners. They have a large fuel tank allowing for long stints between stops. There are lots of bag and windshield options, and endless accesories. There is also lots of community support, tons of info out there. Guys are putting 100,000+ miles on stock motors, which is outstanding for a motorcycle. I have an SV650, which uses the same motor. Its no race bike, but it has a nice broad torque curve that makes it easy to ride slow and fast. The reasonably low displacement also means that vibration is hardly an issue. Check out
http://www.stromtrooper.com/ for more info. This is a great option for long rides, or weekend cruises in the country. I commute 35-40 miles a day on my SV.
There are similar offerings in the sport turing class from Yamaha, Honda, and Kawi, I just know the most about the Vstroms.
Another noteable bike to consider would be the Honda VFR 800. Great sport tourer. The VFR may very well be my next bike, although I am keen on the 1200cc model......
Adventure bikes are similar, but turned up to 11. Personally I would love a KTM 990 Adventure, Dakar. If you want a bike that will go anywhere, in any turrain, in any weather, that is the bike to have. There are many other adventure bikes out there most noteably BMWs offerings. BMW makes a bunch of really sweet touring, sport touring, and adventure bikes. The price point is a bit high though.
It really comes down to what you want to do with it.