Front end vibrations are not normal, doesn't matter if they are common.
Some reasons for a front end vibration could be an out of balance wheel, loose or worn wheel bearings, worn tie rod ends, worn ball joints, centre wear on steering rack, bad tires with split belts or blisters, warped brake rotors.
Going by the age of your car I'd start with a tire roation and see what happens, next I'd go to the brake rotors, probably need a brake job anyway by now.
2006 DTS Performance - L37 32v Northstar NHP V8 292 HP - 1 of 1
1999 STS - L37 32v Northstar V8 300 HP
1998 Deville D'Elegance - LD8 32v Northstar V8 (Sold July 9, 2011 with 225,000 km)
1993 Fleetwood - L05 5.7 TBI V8 (Sold July 18, 2012 with 308,000 km)
1999 GMC Suburban SLT- 5.7 Vortec
1998 Olds 88 LS - Series II 3.8 V6
1973 Pontiac LeMans GT - 454 V8 1 of less than 5