LIE (I-495) isn't too bad in my area, but as you get closer to NYC, it starts to suck tremendously.
Sunrise Highway (NY 27) needs to be made three lanes each way much further east.
The two-laned parkways (Northern State, Sagtikos, Southern State, Meadowbrook, Wantagh, Sunken Meadow, Robert Moses) need more lanes and better merging lanes.
As for other roads, Montauk Highway near me is decent other than the part of it in Mastic/Shirley and going into Southampton (before it turns into Hill St.).
Jericho Turnpike/Middle Country Road (NY 25) is littered with too many businesses, lights, and cars and in some parts is bumpy as hell (just east of Smithaven Mall).
William Floyd Pkwy. and Nicolls Rd. in any other area would have been upgraded to interstate quality but on LI, they're just piddling 4-lane Suffolk County roads with lights.
Rt. 25A (Northern Blvd. in Queens and most of Nassau, and just called 25A in Suffolk) is kinda bad.
Nesconset Hwy./Smithtown Bypass (NY 347) sucks horribly.
Veterans Hwy. (NY 454) is okay.