Just let's review the advantages

Many Vegas visitors have an overcrowded experience on Vegas strip buses, so they give up the idea of bus riding.
Simply planning routes that use residential buses as much as possible, or free shuttles with residential routes eliminates the overcrowding and lowers the expense.
Just a couple examples:
Going from downtown to Mandalay Bay is a long journey even on the SDX bus.
A good alternative is to catch the WAX at Binions and ride to Tropicana. Then cross the street and take the free shuttle from Excalibur to Mandalay Bay.

Going from Palace Station (where maybe you have free nights from MyVegas) to stay downtown for a couple nights seems a challenge that includes bus stops that feel less than comfortable with luggage.
A good alternative is to take the free shuttle Palace Station offers to the airport and then board the WAX for a quick ride downtown.  It might take a bit longer or seem like you are backtracking, but it might be more comfortable and eliminate luggage on strip bus.
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The bus is less likely to cause injury.  Some statistics suggest that the chances of being killed in an accident on a bus are 40 times less likely.  Certainly you will find that you are less affected by locals with road rage, tired or drunk tourists doing erratic things, or wild kids racing down streets.  It also protects you from your own exhaustion or over consumption of free alcohol. 

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There is no tipping on buses.  Fees are reasonable.  If you know how to buy a 15 day pass, fees are low.

Buses are particularly frugal for solo travelers or those over 60 who pay half price on residential buses and may buy passes that bring the cost of unlimited rides down to about a dollar a day. 

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If you want to do a coupon run to try an offstrip buffet or use a matchplay,  already having a bus pass makes the trip in one sense free and adds to the value of hopping about for frugal deals.
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With a smart phone you can read bus schedules or actually check to see exactly when the next bus will arrive at a stop.
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Buses can get you to out of the way, fun places that most tourists miss.  Perhaps you'd like to see the cactus gardens or the art museum on the University of Nevada campus.  Perhaps you'd like to scope out some off strip eatery with good reviews and prices well below those on the strip.  Perhaps you'd like to skip gambling one day and play old pinball machines.

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Buses allow some very interesting day adventures.  For example, you can start downtown and go our Boulder to play around at Sam's town.  Then take the 202 to the Gold Coast.  Then take their free shuttle to the Orleans.  Then take the 201 to the NYNY area of the strip.  An finally you can head back to downtown on the SDX.
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Buses are a way to meet people.  Strike up a conversation and ask a few questions and you may gather some incredible stories.

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Buses make a smaller carbon footprint.

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The savings in gasoline alone make buses a frugal choice.