GDL, in the vain of Los Angeles, USA, requires the use of street transport mostly, as it's a sprawling city and doesn't have such an excellent subway or metro grid. If you wish to take a cab, do. Unlike el D.F., there aren't a ton of pirate cabs, so feel safe --that is, unless the driver's erractic turns and accelerations are making you cross yourself, kiss your thumb and pray a padre nuestro. In this case, say> "Señor(a), tranquilo. Maneje más despacio, por favor."
However, occasionally, as in any other large city in the world, taxi drivers may attempt to take advantage by charging in excess of what the taximetro reads. The city is broken down into 3 tarifas. 1-within the 4 municipalities (Tlaquepaque, GDL, Tonala, Zapopan) up to 22:00. 2-within the 4 municipalities between 22:00 and dawn. 3-outside the 4-metro zone. It should be of prime importance to ensure that next to the initial charge of 7.70 pesos on the taximetro a number reads 1. If it's between 2200-dawn, of course, it should read 2. Outside the 4-metro zones- 3.
If you'd rather not deal with this, you can -- before entering the taxi -- ask the cabby how much to 'X' place. It's probably in your best interest to buy a street map (don't pay more than 80 pesos for the Guia Roji) and have some idea of the route you think might be good. The driver may suggest another route due to traffic, construction, etc, at which point you'll have to risk heeding the "advice" or not.
Mexico has a world-class bus system that's more comfortable than an airliner, and ticket prices are hundreds of dollars cheaper than even the discount flights. The express buses don't delay with too many stops, but we did enjoy the route through the Tequila Valley on our way to Puerto Vallarta. Guadalajara is at a relatively high altitude, so the bus basically wound it's way down hill, with the Tequila Valley being roughly mid-way between the two cities. The picture here is of a typical Mexican bus station. Buying tickets is easy, just make sure you buy them from the cashier at the window, not a guy selling them along the loading dock. Security for luggage is very good, and must be checked through a screening system like an airport. We didn't buy tickets in advance, as I recall, but it's possible that purchasing a few hours in advance will ensure a seat. It's a good idea to walk out and inspect the bus before hand if trying to go the economy route. We found that it's best to not try and save a couple dollars on the ticket price because that may be reflected in the maintainence quality of the bus.
I had to give you one more tip for taking the bus. Every so often, a guy will come on selling beauty products, candy, begging for money, or more commonly, singing and playing the guitar. He will stand and play 3 songs as the bus sways back and forth (worth the money just to see him stay standing), and afterwards he will come by with his hand out...hey, at least he´s earning his keep, right?
The one good thing about the buses here is that they come quite often, the bad thing is that if they don´t feel like stopping, they won´t...it costs 3.50 (pesos) to take the bus, and sometimes they will pack you in there tighter than a sardine can, and other times they will drive right by you even though there are only 10 people sitting on it. I could go on and on, but I will give you only one more tip. Apparently it is not considered rude to sit on the outside of the seats and not let anyone sit beside you...at first I was horrified, but I guess it does make for a more comfortable ride...so back off granny, I got here first...
Guadalajara has a nice metro system. See map and details in the websites below (first one in English; second one, official site, in Spanish).
One token for one ride is 3.50 pesos (approx. 30 US cents)
The Tarjeta Inteligente (Intelligent Card, see picture) is a rechargeable contactless cashcard. It costs 20 pesos (about US$1.80), 6 for the card itself and 14 to use in metro trips, and you can recharge it in amounts of 10 to 200 pesos (about 1 to 18 dollars). (exchange rate 2004)
There are tons of public buses in Gdl. to take - but be sure that you are sturdy on your feet and strong to hold on. The drivers are FAMOUS for their terrible driving and accidents with pedestrians. They will RUN YOU OVER so do not count on them stopping. It would be better to take a taxi - they should use a taxi meter but many do not. So be sure that you figure out the price BEFORE you get in the taxi. Your hotel can tell you more or less how much a taxi will cost from one part of town to another. It is not the custom to tip taxi drivers in Mexico.