On flat ground, it's all about the green complexes. The greens and their surrounding hazards dictate strategy, add interest to play, and challenge to scoring much more so than anything else between the tee and the hole (ie. bunkers).
One of the best "case studies" in creating a great golf course on flat ground is Essex G&CC in Windsor, Ont. At Essex, in 1928-29, Donald Ross literally planned 18 varied and interesting greens but very little else. The fairways were originally in excess of 50 yards wide with a few sporadically placed fairway bunkers here and there.
Essex is fantastic in that it proves how simple golf course architecture can be -- a good routing, and 18 varied and interesting green complexes. That's all you need. None other than Ben Crenshaw emphasized this point when he visited Essex a few weeks back during the Canadian Senior Open.
As for Essex' best hole? See the 388 yard par 4 16th in its original form. The green is divided into three separate "cupping areas" separated by gentle terraces.
Most interesting is a lobe of green surface (missing today) that jutted between to greenside bunkers at right. When the pin was tucked back there it was imperative to drive down the left side of the fairway -- especially during the summertime in the days before fairway irrigation!
Conversely, a hole cut on the high plateau at back-left of the 16th green necessitated a tee shot down the right side of the fairway -- which not longer exists.
Three bunkers down the right side of the 16th hole were added in the early 1980s, resulting in a significant narrowing of the fairway. The only option off the tee today is left, or right and short of the bunkers (220 yds. or so).
Essex' 16th is today a perfect illustratation of the course's evolution from a classic Ross "second shot" design into one that places a premium on straight driving.