So I've decided to sum up everything I know about audio quality in order to make a final, definitive statement and put the topic to rest. What I've found is that CD quality audio (sound sampled at 44.1Khz/16 Bit) is perfectly adequate for 90% of uses, and is even overkill in some cases, such as recording a very lo-fi source. It thus follows that a vast majority of samples, recordings, etc are in this form. When making music digitally we will most of the time be dealing with audio in this format. So we of course need a way of dealing with it, and incorporating it into sessions with higher quality audio.
Another basic point is that everytime you convert your audio to another sample rate, or bit depth, you are reducing it's quality. My earlier posts were simply pointing out ways of making the reduction in quality as minimal as possible, preferably pushing it down to inaudible levels. It is true that most of the gradations of quality I talk about are close, or very close to inaudible through the average consumer stereo or speakers. So if you don't really care about hi-fidelity listening, don't want to think about how something sounds through even average studio monitors or medium quality headphones, than by all means use CD quality and go outside, play a round of golf, read a book...

OK, I'll assume only the hardcore audiophiles are left. So, what is the best workaround for CD quality audio? Well, if something is already in this form, I don't really recommend upsampling it, because you'll have to convert it back down anyways, and you should ideally do as few conversions as possible. All you can do is save any audio you export as a
32 bit float to make sure that all the processing you do in your DAW is saved. The only problem with this is the same as any other kind of high-quality file format: the increase in file size, in this case it is doubled over CD quality. But it is only necessary to save to this format during the production process up to the final export. When you export your finished track in the 32 bit format, this is where all those conversion utilities I mentioned before come in handy. Use the highest quality
dithering algorithm you can get your hands on, such as Isotope RX or the Waves Ultramaximizer series (or failing that the default settings in your DAW's export menu) to convert your 32 bit master down to 16 or 24 bits.
If you have material at some oddball sample rate that is not CD quality, like 48K or 88.1K, well it's up to you if you want to convert it down to CD-Q or up to 96K or 192K, which is what most interfaces run at these days. Technically it's better to convert down, keep everything at a single rate, than it is to convert up and than back down. It's also less hard drive space, but it's again completely at your discretion what you want to do. Remember that a resampling algorithm can never "add" anything, it can only NOT take away what's already there. Also sometimes you have too many files, or too large of files, to resample easily. In this case just throw it into your DAW, use it's high-quality sample rate conversion setting, and focus on the music.
The most headache-inducing situation is where you have a session with audio at a variety of sample rates, as well as recorded material at a higher rate, again preferably the highest quality your interface supports. It helps to remember that a chain is only as strong as it's weakest link, the lowest quality element in your mix is what everything else hinges around. So to prevent headaches just run your session at the rate of the highest quality audio with the high-quality SRC mode in your DAW on. When your track is finished print all the audio at the session rate, mix it, and export it at 32 bit float. Than do a single sample rate conversion and dither with a mastering utility or r8 brain/SoX. The latest version of Audacity is now using the sox resampling library, so yet another reason to check it out!
If you really need to conserve space, you can follow the same steps, but change the session rate to 44.1K at the mixing stage. That way your printed audio tracks will be much smaller in size, meaning less disk space used overall. You can also chuck the session onto an external drive when you're done, provided you've collected all the samples and saved (Your DAW should have some kind of setting for this) You should still record any recordings at the highest sample rate/bit depth your gear supports and keep them somewhere, as well as export at 32 bit float until the very last stage of the mixing/mastering process. If you follow these steps, you shouldn't have to think about audio quality, and you can focus on the content of your music. While it's nice to forget the technical aspects and craft your sounds, it's also important to be conscious of what you're doing. I mean, if changing some settings can improve the sound quality of your projects at the expense of a little disk space... Why not do it? disk space is only getting cheaper, why not be future-ready?
Well, that's just about everything I know about audio quality summed up in a practical manner. Hopefully I'll never have to revisit this topic until some new kind of technology comes out which renders everything I know obsolete. Until than...