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The classical sound-ideal differs from the one of steelstring guitars for example. Therefore piezzo-pickups or mics inside of the body are definitely a don't if you want the real classical sound! It is also quite common to put some of the live-room-sound to your recording by placing the mics at a certain distance to the guitar. That requires, however, a good sounding recording room. If you don't have the propper room, you have to put the mics closer to the guitar and add some reverb later.
Usually large single diaphragm condenser microphones are the way to go. The whole of the sound should be smooth and warm. Too much emphasis on the high range is rather not recommended. If you got mics that have very dominant heights you will even have to high-cut the recording a bit.

You´ll get the best sound out of those above mentioned large single diaphragm condenser microphones. Their sound is a bit smoother and they don't produce as much background-noise as regular small-diaphragm mics. You should get the best microphones you can afford. A good choice are two Beyerdynamic MC 740 set on cardioid (polar pattern) and some bass cut at 50 hz. Some mics have a bass cut starting at 80hz, but thats not good for it will cut some of the vital bass frequencies of the classical guitar.
A very important part of the whole process is the preamp. Try to get at least a halfway decent one. A good choice is the Gold-Mike by SPL - its not too expensive and sounds natural and warm plus it isn't just a simple preamp - it also has some additional options like low-cut and presence.
When you go digital you have to use a good D/A device. You should always record at 24 bit at 48 khz. Higher sampling rates (96 or even 192) do not make any difference for a regular CD-recording. But don't use 16 bit. 24 bit is much more accurate and brilliant.

Here are some examples i found on the net, showcasing some of the differnt microphone positions/variations:

Ex. 1 - Recorded with a large single diaphragm condenser mic (LSDCM), distance 20 cm (aprox 7.87 in.) pointing towards the bridge a bit below the soundhole

Ex. 2 - Same mic, same direction, distance 45 cm (17.7 in.)

Ex. 3 - 'close micing' again (7.87 in.), this time pointing towards the wood (top) below the bridge

(i dont have sound examples for the following positions - just go figure)

4. same position, 17.7 inches

5. Stereo with two LSDCM. position 1: rear position (as in example 3) position 2: top below the neck - both microphones adjusted paralell

6. ssame as 5, but this time "directed" (same axis, but 90 degrees turned towards eachother)

7. same as 6 - but 17.7 inches

the soundexamples should be listened to with good headphones since some of the very subtile differences might get lost on cheap speakers.
those recordings have been made in typical home-recording situations.

The room had a normal wooden parquet and was not dampened nore otherwise acustically enhanced. hard surfaces dominating. no curtains or upholstery whatsoever.
the recording equipment was rather home recording standard and is affordable: two AKG C-3000 mics and an old Roland VS-1680 EX Hard-Disk-Recording-Workstation. nofurther onboard equipment, no EQ, no effects. Samples performed by Bernd Maier of the Barrios Guitar Quartett.

hope that helps! ;)