We had a 2003 Suncruiser. The Itasca division is posioned by Winnebago to be an upscale divison, but in reality the Adventurer and Suncruiser are 985 the same thing. The only "upscale" features are decor. If you think either one looks good I'd let the dealer be the deciding factor between the two. When we went shopping we found an excellent Itasca dealer nearby while the nearest Winnebago dealer wasn't very helpful so that sealed it for us. However, your location may have the opposite scenario so that's something you'll have to check out.
As to gas versus diesel, well there are definite advantages to a diesel over a gasser. They handle better in the wind, the ride smoother, they have more torque for climbing hills, they have greater carrying capacity, etc. Oh, by the way, they cost more too.
A Suncruiser will take you any place a Meridian will, it's just that the Meridian will get there in greater comfort. I can drive all day in my Bus and never get fatigued compared to my Suncruiser. If you move around often enough I know you would appreciate a diesel. Again, your type of RVing, lifestyle, and financial situation will determine whether or not a DP is for you. If you want more specifics on what I found feel free to PM me.