WASHINGTON -- President George W. Bush called the wars in Iraq and Afghanistan a part of the nation's destiny and described the American men and women who've died there "a new generation" of heroes.

Bush laid a wreath Monday at the Tomb of the Unknowns at Arlington National Cemetery -- his fifth visit there as a wartime president.

In remarks afterward, he said the wars in Iraq and Afghanistan follow a rich tradition of similar American sacrifices throughout the country's history.

Bush praised those who continue to volunteer for the U.S. armed forces despite the mounting casualties in Iraq. He said they're not "fatalists or cynics," and that "they know that one day this war will end, as all wars do."

Bush added, "Our duty is to make sure this war was worth the sacrifice."

Earlier, Bush met privately at the White House with families of some fallen servicemen and women.

Sunday Observances Cover Wide Range

From street-theater protests and biker parades to quiet, poignant remembrances, the nation Sunday prepared for a wartime Memorial Day while remembering fallen veterans killed as recently as this week.

Volunteers with Veterans for Peace set up a memorial on Santa Monica Beach in Santa Monica, Calif., with red crosses representing 10 dead soldiers, owing to the increasing number of dead.

In addition, 22 faux coffins draped in U.S. flags and accompanied by blue crosses represented the total killed this week. A wall holding hundreds of photos of fallen soldiers in Iraq was also set up on the beach.

Slideshow: War Dead Remembered At Arlington West Memorial

In Washington, President George W. Bush was greeted by a throng of bikers in the nation's capital as part of Rolling Thunder, a nonprofit veterans group that works to find American prisoners of war and soldiers missing in action.

Sunday marked the 20th anniversary of Rolling Thunder's annual Ride for Freedom through the nation's capital.

Video: U.S. Remembers Fallen Soldiers

Spectators lined the parade route to show their support for the event and their concern for U.S. troops.

The parade of motorcycles began at the Pentagon, crossed the Memorial Bridge from Virginia into D.C. and gathered at the Vietnam Veterans Memorial.

Leaders of the group then paid a visit to the White House, roaring right up the mansion's driveway. Bush stood at the South Portico to meet them.

Bush welcomed the leader of the motorcycling group, Rolling Thunder founder Artie Muller, who led a group of 13 visitors who roared up the White House driveway on eight motorcycles.

The president gave out handshakes and hugs, took a look at the gleaming bikes and then invited his visitors into the Oval Office.

Muller said he presented a series of concerns to Bush. Among them are the way the Defense Department classifies missing and captured troops and the plight of soldiers who have been discharged from military hospitals and are having trouble supporting their families.

Muller said Bush always has been very honest and supportive of veterans' issues.

Vet War Protesters Stage Guerrilla Theater In NYC

Some vets maintained a more contentious profile on Sunday. Military veterans of the Iraq invasion staged some guerrilla theater in New York to protest the continued U.S. military presence there.

The half-dozen veterans protesting the post-invasion occupation wore camouflage fatigues and pointed imaginary guns at a crowd of anti-war protesters playing Iraqi civilians. They threw some roughly to the ground and handcuffed them.

The protest was organized by Iraq Veterans Against the War. One of the vets said conventional methods of getting their message out have not succeeded. They hoped Operation First Casualty will break through. The name recalls the adage that truth is the first casualty in war.

Combat Boots Mark Fallen U.S. Troops In Chicago

Meanwhile in Chicago, more than 3,400 pairs of combat boots representing U.S. troops who have died in Iraq were lined up in military formation in Chicago's Grant Park.

The memorial display was a project of the American Friends Service Committee. It was a traveling exhibit called "Eyes Wide Open: the Human Cost of the Iraq War."

Civilian shoes representing a fraction of the Iraqi civilian casualties are also on display.

The display -- the size of nearly two football fields – was set to be in Grant Park through Memorial Day.

Each pair of boots is tagged with the name, age, rank and home state of the fallen serviceman or servicewoman. Loved ones have attached personal memorabilia to many of the boots. The exhibit first opened in Chicago's Federal Plaza with 504 pairs of boots in January of 2004.

The American Friends Service Committee is an international social justice organization.