We use Cvent Event Management for the registration of some of our larger signature alumni events throughout the year. It allows for our registrations to be complex and we have worked with a third party for the information to transfer to our CRM.
Cvent Event Management is the caviar of event management tools. It is expensive, but you get what you pay for. Again, it is useful to us for our larger complex events that involve multiple invite lists and sessions, but is cost prohibitive when it is a basic yes/no scenario. It is also nice because it allow us to take donations through the registration.
It is well suited for a complex event that involves multiple sessions that are not open to everyone or that has multiple invitation lists. It is cost prohibitive for us to use it for simple yes or no invitations for something like a dinner or reception.