If 250mm is far enough, then the DA18-250mm is the perfect all-around lens.
It is one of the best all-around lenses, across all brands. Like any zoom, it has some shortcomings, but the overall IQ is excellent. The flexibility with its focal length range is great, and the absence of lens swapping is a nice feature.
The Pentax DA18-250mm and its sibbling Tamron 18-250mm have been discontinued but you may still find some excellent condition 2nd hand lenses at the MarketPlace (in this Forum) or specialised shops like
www.keh.com.
The only downside of the DA18-250mm is (in my opinion) the low light conditions. But most zoom lenses will have this problem.
Hope that the comment will help...