My 3 year-old (unneutered), Denali, is very well exercised and has enough playtime throughout the day.  The problem is he is very needy for attention, especially when other people are around.
Even when my friends bring over their dogs for playtime, he will play with them briefly, but if we are all sitting down, he will come over to me, stare at me and begin to whine.
I have tried everything including ignoring him until he stops (which can make conversations difficult), bones, toys, playmates, petting him, having others pay attention... (although mostly stick to the ignore him -don't give in to his whines)

Otherwise, almost all bad habits that are known for this breed are under control.  He is a very well behaved and sweet Vizsla.
I don't know which route to go or how to get this out of his system. 

Have you tried sending him out of the room when he whines, one step further than ignoring, excluding.

Welcome to the world of Vizslak! They aren't called 'velcro' dogs for no reason and absolutely crave attention. However, as you have found, there are circumstances where this behaviour is unwelcome.

Is there a particular time when he becomes more needy or whiney? One of our vizslas could eat for England and knows when her meals are due, she will sit and whine and generally make a pest of herself until she gets let into the kitchen...where she can at least smell food even if it's not meal time!
As a breed they are very sensitive, and like I say, crave your attention so a very effective way of curbing this behaviour would be a 'time out'. Whine and you're out! Ten seconds out of the room(quiet) then back in, don't make a fuss when you let him back in, just carry on how you were before, watching TV, chatting to a friend, having a cuppa, whatever. His reward is being allowed back into the room with you :-)

Hope this helps, any other question, fire away!

Emily