Those tour guides have a negative and positive to them. The good thing about them is that you will have someone to take you around the city. Cairo is a huge city and is easy to get lost. But it is better to know someone who lives there. If you are a tourist people are going to rip you off big time. Everything you buy will be really expensive. The travel companies that are going to be taking you around are probably going to rip you off big time too. To just get into the pyramid is like 3 dollars or 15 Egyptian pounds. So it's really cheap. Taxi's can be really expensive for foreigners too but, I think it would be a little bit cheaper. Also you usually can find an Apartment you can rent out for way cheaper than a hotel, but then again these might be hard for you on your trip, and sometimes it's just better to pay a middle man. If you are good at traveling and think you can get around in a very big city like this one and be able to find a cheap apartment on your own (you probably would have to know some Arabic for this), then I would take your own way. If you don't think you can do that on your own and are scared of getting lost I would take a middle man to be safe. Some times it's best to just get somewhere and let someone else do the worrying for you.
Karul Morton: Agreed. There are advantages and disadvantages to using a guide. Moreso, I think there are times when you need a guide and times when you don't. I know that some people think you never need a guide in Egypt, just a good guide book. Eh, I don't know about that. Yes, Lonely Planet and Rough Guide are very good and I never leave home without them, but the prices are often outidated and trying to do major sites while looking at a guidebook means you miss out on the beauty of the site. This is where guides bring that magic to life. A skilled guide will re-create the grandeur of the monuments and take you back thousands of years.
For the larger temples like Karnak, Luxor, Medinat Habu and Denderah I think you need a guide.
For places like the Pyramids, I think a book will suffice.
The Egyptian museum is tricky. Having a guide restricts your time and your ability to move about as you like, but many of the artefacts aren't labeled. My solution was to do it once with a guide and about four times without lol. What can I say? I LOVE the Egyptian museum.
I would say the advantages to using a guide are having a warm, friendly ambassador to the country, having a buffer for the touts, having an avid story teller and transportation arranger.
Disadvantages are time resrictions, unwanted shopping trips (carpet, papyrus, jewellry, perfume) and not being able to haggle below a certain price because the shop owners are obliged to give them a commission.
Ways to get around it -
Arrange for the transportation to come back for you or stay with you separate from the guide. Many times the guides can leave and the driver can stay with you or return for you if you want to see every nook and cranny of a place. More importantly, if you're someone that needs lots of time at sites, be honest with your guide upfront and find one that suits your needs.
Take control of your itinerary. Customized tours are not at all expensive. Book what you need and nothing you don't, which means....
If you want maximum time at the sites, stress before hand that you are NOT interested in shopping trips even if that means you pay more for the tour. Many times, guides will quote you a cheaper price because they know they will make up the money in shopping commissions. It is VERY hard to get out of buying something once a guide dumps you in a store, leaves you to the salesmen and they start laying the guilt trip on you about how everything is handmade. I say before hand I don't want to go because I know I am weak and I never like the cheap stuff lol.
Many guides say they are Egyptologists when they are not. If you are well studied in Egyptology, or it's an avid hobby you wil most likely be disappointed with the majority of the guides. Get a guide from a reputable source (maybe an Egyptology group) or one who comes highly recommended by people at your level of expertise. You will pay more but it will be worth it. If you just want a basic/moderate overview of the sites, most guides will suffice.
Mahmoud mentioned flat rentals. In busy times, many landlords only rent by the week so if you're somewhere for two days getting a flat may be a bit harder. Research prices online before you go or work with a reputable guide to assist you.
As a tourist, you will get ripped off a few times your first visit before you get the hang of things. The key is to research, research, research before you go. This minimizes this alot. Do not blindly trust peple to look out for your best interest. You don't have to have a friend there. Most visitors don't but thankfully, there are many forums and pages like this one that help visitors out prior to landing in Egypt and many repeat visitors who are ready and willing to answer questions.
Have a great trip!
PS. Where is it $3 to get into a pyramid?