The first shot (which I really like) looks like you have a filter on it (the green flare). If so, remove it. Shooting into the sun and filters is not a good combination unless you have a very specific need (i.e., split nd filter). Actually regardless of conditions, only use a filter unless you have a specific need.
The second shot does nothing for me - the scenery is average and the time of day is hurting the image (conversely a similar lighting condition in the first shot is what actually makes the shot). When shooting in the general direction of the sun, you have to really have a plan in place, and it's not there in the second shot. If you had shot that at the opposite time of day you would have had better contrast and nicer skies; right now it's all washed out.
And yes, clean your sensor. I can see the spot in both shots but in the first shot it's obscured by clouds, but it's there.