This company could be huge if given enough time to grow. You are right; any of those names coul take Cvent to the next level and there would be a certain amount of synergies. Unfortunately, it probably isn't going to happen. The only hope is that the purchase does run to the end of the year. That's a very long time for a purchase so anything is possible.
There have been a lot of new deals announced this quarter and many of those will result in much bigger orders... This isn't a story of last quarter so much as a story of what is coming... The CEO should have more to say about forward guidance during the earnings call; until then, sit tight.