Dining Table shape

I am shopping for an extendable dining room table that will function as our only eating space for our family of 4. We want the table to seat 4 easily and be pleasant for 6 (rarely 8).
I'm drawn to round tables because they seem functionally to be better for conversation (we have young children). But, round seems like it isn't the best for efficient use of space.
The dining room is adjacent to the kitchen, and it also functions as a hall to the bedrooms.
The size is 12' x 10'. The kitchen entry is on one of the 10' sides; the hall space occupies the length of the 12' length.
I'm thinking a 45" round is the size that would fit best.
Questions:
Is a round table really inefficient use of space?
If I went with something non-round, what would you recommend?
If I go with round, pedestal or legs? I don't want it to be tippy (still teaching toddlers that not everything is climbable).
How do I go about finding a quality piece of furniture (in the NW)?
Thank you!