Which way is the best for a big design build project? Creating alignments in SS2 then importing to SS4. Or SS4 then exporting to gpk/alg?

There's an entire forum dedicated to the Civil Software.

I wouldn't do much of anything in SS2 at this point if I could avoid it. The SelectServer licensing is going to go offline relatively soon, and the only V8i-type software available for pooled licensing will be SS10 (which is essentially SS4).

That being said, determine which software you will be doing your design in and work in that. You can take certain design elements back and forth, but that only works to a certain point in design.

Just saw that I posted in Microstation forum. Thanks for your answer.

Design Build is a collaboration between consulting and construction. They can be a single entity, but however it's done everyone will have their own software requirements/abilities and all will need to be able to use all the data. I would use current Microstation with whatever application software. Generally you would always use the application to create alignments and such, Microstation just stores the graphics.