"(The 12-acre site) hasn't been a significant factor in our negotiations and we want to be able to negotiate with other parties for non-arena developments," Adams says. "We will continue arena negotiations exclusively with REI for their site."

While all this is going on, a pair of 800-pound entertainment gorillas, Anschutz Entertainment Group and Harrah's, are making positive progress toward a 2008 groundbreaking for a $500-million arena just off the Strip, immediately east of Paris and Bally's. Harrah's says the project remains on track for a 2010 opening.

The duo plans to construct and configure an arena in a manner that will make it capable of housing an NBA or NHL franchise as well as concerts, boxing matches, special events and awards presentations, tournaments and exhibitions. Plans are currently being finalized for submission to Clark County for approval.

AEG is a developer and operator of sports venues, such as Staples Center, The Home Depot Center, Target Center, London's O2 Arena and NOKIA Theatre Times Square, and it has an existing presence in Las Vegas through its subsidiary AEG LIVE, which oversees programming for the Colosseum at Caesars Palace and other venues on the Strip.

By all accounts, the AEG/Harrah's arena will be built, with or without an early commitment by a major league sports team to call it home. It's unclear if the same can be said of the Downtown arena, which may be one of many reasons for the negotiation extension.

REI Group president John Weaver told Globest.com earlier this year that the Harrah's project is meant to compete more with the other near-Strip entertainment venues operated by competing casino-resorts such as MGM and Mandalay Bay and Caesars than a Downtown arena. He is confident the two arenas can coexist.

"We were always aware that Harrah's had included this type of entertainment venue as part of their master plan, and that AEG has a tremendous presence in Las Vegas and a great reputation for delivering high quality events and close ties with the NHL and other leagues," he said. "We believe our location and access and cooperation with the city sets us apart; I think there are certain events, including those that require a casino-neutral location, and other opportunities for which we may have an economic advantage."