ETABS is a powerful building design package. In some ways, it's awesome, but CSi insists on including enough stupid crap that I'm not sure it would ever be my first choice.
We used it extremely effectively for tall buildings with shearwalls. That was our main usage.
About 3 years ago, I gave its composite beam design a good workout and found pages of bugs, stupid defaults, unexplainable output, etc. I'd go as far as to say that some of it was just plain wrong. The noncomposite beam stuff had lots of weird defaults also.
CSi also has some very strange ideas about ergonomics. For example, units are always either kip/inch, kip/ft, lb/ft, etc. Try entering your concrete material properties when you want unit weight in pcf, E in ksi or psi, etc. You have to either calculate some of the parameters in unnatural units or enter some of them, exit the menu, change the units, and re-enter the menu for the others. I complained about this and they acted like I had two heads. I can't think of another modern program that does this. RISA for example has a screen where you can specify that lengths are ft, loads are klf, or whatever is natural for you.
I use SAP2000 A LOT and it's similar. Very powerful, but has a lot of the same "Why the @#$# would a programmer do that!?!" issues.
The main difference is that SAP is more general purpose. For example, it uses member geometric stiffness matrices, so it can do buckling analysis. ETABS uses story geometric stiffness matrices, so it can't. The story Kg's have the advantage of not requiring iteration for second-order analyses because the axial load in the total story never changes after the first iteration. SAP has some support for cables and more nonlinear options than ETABS.
ETABS also has things like shear wall piers that help when trying to size the rebar between or over doors, etc.
You may consider RAM Structural System, which has a pretty good concrete design module. We are using this for several years and found to be quite good. The big advantage of RAM is that you can generate concrete beam & column schedule. With ETABS you have to buy CSI detailer which come as an option with SAFE program. To generate any detailing out of ETABS you need to have SAFE & CSI detailer (it costs about 10K for all 3). RAM would be much cheaper.
