If you are itching to get a new toy, and have an extra $800 or so lying around, I agree with the 70cc+ saw for what you describe. And at least a 24" bar, and a 28-32" perfered. But a 24" will do and is a good all around size on a 70cc saw.
There are pretty much 3 excellent saws to choose from, Husky 372xp, Stihl 440/460, and Dolmar 6400/7300/7900.
All are top notch.
Dont mess around with the smaller non-pro grade saws like some mentioned. No offense meant to anyone, but a MS290 or MS310 would NOT even be near the top of my list of saws to choose for what you describe.
The MS290 "FarmBoss" may indeed be the best selling saw in the world, but that doesnt make it a good saw. IMO, it is a terrible saw. Heavy and slow cutting. And by terrible, Again I dont meant to offend anyone. It IS a reliable saw and will cut wood. But when compared to others in its class and for similar money out of pocket, there is MUCH better options.
And I dont know how your neighbors are, or how you are, but I personally wouldnt loan MY chainsaw to ANYONE. It is just one of them things that, guys who run saws a lot, understand.
So IF you can still find some saws in your area, look at the models I mentioned. Anything under 60cc isnt going to be a big enough step-up over your MS250 to be worth the money.