Is it a real pain to replace front sway bar bushings on a 2011 Nissan Sentra ?

SOURCE: Front Left Sway Bar Link

The front stabilizer shaft (sometimes called a sway bar) is mounted to the top rear of the frame and to the lower control arm. The shaft is attached to the frame with clamps and rubber insulators and to the control arms with insulator links.

Try http://www.autozone.com/shopping/repairGuide.htm

SOURCE: 2003 Dodge Caravan Front end clunk.

Had similar problem with 2003 Dodge GC. Replaced the parts you mention + rack & pinion, then to fix the now noticable whining noise, replaced power steering pump and pulley. Fortunately was under an extended warrentee at 46k miles.

SOURCE: i have a2001 cherokee sport

Clunking noise in the rear of the vehicle is a broad statement. When is the vehicle doing it? Is it all the time or just over bumps? Is it happening only going around curves? Is it a constant bump that speeds up and slows down with the vehicle speed. You would be supprised how many clunking noises can come from the driveline not the suspension. It could be anything from a bushing to your rear differential getting ready to grenade.

SOURCE: 2002 caravan clunking problem

may be boll joint
or sway bar link .

SOURCE: 2002 clunking problm

Check the macpherson struts to ensure they are not loose.  One way to check is visually in the engine compartment.  Check the top of the struts to ensure the nuts are not loose.  Another is to raise the side of the van where you hear the clunk.  Raise it so the wheel is off the ground.  Grasp and shake the strut to see if it is loose.  The struts should not be loose, but you never know.  As the strut is certainly ivnolved in bumps and rotates when the wheel turns, I would check there since you have already explored the bushings and links.