Flights and Arrival/Departure: Always try to fly in Sunday. Friday and Saturday nights the hotels are 300-400% more expensive then the rest of the nights. Always try to check in Sunday morning or afternoon, and check out Friday morning. If you do arrive Saturday night, just check in your bags with the bell boys, and stay up all night. Once it's 8AM, just check in early with the hotel. Some charge a fee, but it is very small, usually $10-$20. Usually if you are polite, and ask, they will waive it.
5 nights, 6+ days is always enough time in Vegas. You will find after the 3rd or 4th day, if you are partying a lot, or even just walking around, you will get worn down and the 6th day you can't wait till you get home. Friday and Saturday night do have a lot more people, but not to worry, there will still be plenty of partying to do during the rest of the week. There are always people ready to party in Vegas.
Hotels: Don't ever cheap out too much on hotels. Try to find one close to strip. Don't ever stay at Circus Circus, or even Strat, you will wear yourself out in the heat/walking, or even worse, over spend on cabs. Don't EVER take the local bus in Vegas. Just don't.
Another important reason not to cheap out is you don't want bed bugs, or sheets that are rarely cleaned, or toilet seats not disinfected. It's not worth saving $20 a day, just to spend it on cabs or meds for your bed bugs. The best value hotels are Monte Carlo, and Treasure island. TI has updated rooms, and excellent cleanliness. They also have safe in the room and a fridge. Huge pluses. Monte Carlo does not have a fridge, but they do have a lot of stores/food court and probably the best location on the strip. Pretty much in the middle of everything. Rio is also decent as well, large rooms, but they are off the strip and will require walking or cabbing. So I would stick to MC or TI first trip. Both have free wi fi as well for guests. MGM is also a nice hotel, but its dated, and over crowded.
Cabs: If you are going to cab, always shout out around you "IS ANYONE GOING... insert your destination" 90% of the time, someone will split a cab with you. Always ask for flat rate, and pay upfront so you have to disputes. Don't let cabbies think it's your first time. Say "Whats the flat rate again too...... it's been a few months since i've been here" etc...
Food: Once you check into hotel, go to the 24 hour grocery/pharmacy, Walgreens or CVS are both on the strip (googlemap it). Buy lots of bottled water, snacks, etc.. to curb your hunger at nights. If your tight for money, budget 20-$25 a day for buffet and eat around 3pm. Have a snack in the morning and one late at night, and pig out at 3pm. It's not the best thing to do long term, but it will tie you over so you don't end up spending $50-$70 a day on food. Don't eat too early or too late, always space it out in the middle of your day so your snacks can hold you over.
Cell: If you are from Canada or another part of the US where you dont have state/national coverage, pickup a trac phone at the pharmacy. It's $20 and gives you 200 local minutes and of course a cheap but decent LG phone. You can use this phone to give out your vegas number to person, girls, randoms, etc... so you don't give out your real number and as well, don't have a lot of extra roaming fees. The trac phone is available at CVS and Walgreens.
Girls: If you can't find any, just go to backpage or eroticreview and find a local INDEPENDENT girl. Call, ask for price for what you want. Some will try and scam you and say $200, but when they arrive say that is just their fee to show up and charge you more. Go thru everything on phone. Tell them you are here often and if she does a good job, you will use her again. She will call you back at your room to verify you are there. Don't let them know you are new or won't be back often, you will just get a quickie. Remember they will not invest in you if they think you are not coming back. You should find a girl to do everything for $300. Once you have settled on time and place, meet them in lobby to be sure they are who they say they are and you approve.
Don't EVER use the flyers, they are fake pics and have pimps. DON'T EVER try to pickup on the strip. That is where LV Police do stings. Casino pickups are ok, but again, iron out all details in casino. Be firm and confident. Be the boss. Don't be naive. NEVER take her first offer. Say "You can try to find a fat old slob for $500, or you can spend an hour with me and have a good time for $250" etc... They will always cave around $250-$300. Never pay more then $300.
Good Buffets: Bellagio is pretty much the best. 3pm is a good time too cause you skip the lunch crowd, skip the dinner, and don't pay dinner prices at 4pm. Wynn is overpriced. Paris is also a great choice. Each are $20-$25.
Massage: If you have luck at the tables, spend $160 and get a massage at the Bellagio. Ceasars is also good, but don't go to Palazzo/Veneitan. Bellagio is the best. Go in, pay the $160 for 60 min. Go 1 hour early, take a shower, warm jacuzzi, put on your robe, and follow the guides. They are worth it.