I thought this was interesting – an old and new Stadium Comparison from the Yankees official site:

Comparison	Current		New

Opening Day	1923		2009

Field Dimensions	Left Field 318'	Left Field 318'
		Left Center 399'	Left Center 399'
		Center 408'	Center 408'
		Right Center 385'	Right Center 385'
		Right Field 314'	Right Field 314'

Seating Capacity	56,886		52,325
				(Including Standing Room)
   
Seat Width	18" to 22"	19" to 24"
Legroom Bet Rows	29.5"		33" to 39"
Cup Holders	N/A		In all general bowl seating
   
HP To Backstop	72' 4"		52' 4"
Private Lux Suites	19		56
Party Suites	XXX		410

Avge Concourse 	17'		32'
Rest Fixture Ratio	1 per 89 Fans	1 per 60 Fans
Family Restrooms	N/A		12
   
Stores (Sq Feet)	Approx 6,800	Total Approx 11,560
				Main Store 5,825
				Collectible/Art 1,735
				Home Plate Store 2,435
				Great Hall Store 1,565

Video Scoreboard	25' by 33'	59' high by 101' wide
   

It doesn’t seem all that “more roomy” to me in terms of the seats and leg-room (in some spots). But, the bigger concourse areas seem pretty good.