First, acknowledge the fact that you are wearing a suit because the environment you are in values aesthetics over function in terms of clothing -- i.e., you are signaling to others with your clothing. Thus, you might well want a knife that complements the signals your suit is emanating.
For a knife that places high priority on aesthetics, look for one designed by an Italian. good Italian design tastes tend to be among the best, whether in men's suits, sidearms (e.g., Beretta), or cars. If you want to confine your choice to an American designer, look at knives by Elisha Isham.
Isham prioritizes artful design, but then finds a way to make his designs functional. Within your budget are his Civivi Anthropos and the new Civivi Plethiros. Both have D2 blades, with the Anthropos at 3.2 inches for $80, and the Plethiros at 3.4 inches for $75. The ultimate Isham suit knife I think would be the We Pleroma, with a 3.0-inch, M390 blade for $300. You pull out a Pleroma with its sacred geometry and you're going to have the attention of everyone within sight and you'll be sending positive signals.
If you are traveling on business and might visit such tyrannies as Chicago or Boston, you will want a blade no longer than 2.5 inches. Many other jurisdictions limit blade length to 3.0 inches. Besides, a sub 3-inch blade is less likely to alarm the city slickers in the crowd, especially if the blade has a less threatening profile, e.g., a sheepsfoot.
Kizer has multiple titanium framelocks that would make great suit knives; e.g., the Vagnino-designed Zipslip, the Lundquist-designed Feist W.
) the CRKT Swindle (the rippled one in 12C27) is something different and interesting; I suggest you take a look. 
I'm aware of the CRKT detractors around and all I can say is I have at least 8 of them and ALL were very well done. Maybe I'm just a special person. 
