One of my favorite things to do is take a tour of fabrication and assembly houses as often as I can. You should make every attempt to do this if at all possible. It is very important to get both fab and assy involved in your design as soon as possible - long before completion. Get documentation from as many fab/assy houses as possible. Try to insist on talking with the people that actually do the work.
If you have not already done the above, you will be surprised at the help you get because they want your business. They know that even if you do not go with them for that design for whatever reason, there is a good possibility you will feed them in the future. Directly or indirectly. I might still have contacts in the Southern California area if that will work for you. In all cases, anyone who will not give you the time is a waste of time.
I have acquired some pretty tight footprints and placements by keeping everybody in the loop. However, I will not disclose them because of NDAs in place, and/or I have no wish to burn any bridges.
You already have a great resource with the internet. Websites usually have their capabilities listed in some form or other.
That being said, the technology is always advancing. You may get better results than I have, but I will help with what I can; There is a lot of competition in this world so when I will not give you the answers, I *will* show you where to find them.