Head to Head
Let's review: The Spanish verb querer, when applied to objects, means "to want." When applied to people it usually connotates affectionate love, but can be used as part of a phrase to express physical or sexual desire.
The Spanish verb gustar literally means to be pleasing or to bring pleasure. When applied to objects, this is usually perfectly innocent. Te gusta la bicicleta? is less likely to be translated literally (Does the bike bring you pleasure?) as much as figuratively (Do you like the bike?). When applied to people, however, the literal interpretation may be correct: Me gustas, or "you please me," can be interpreted in any range of desire and physical or sexual connotations. Or it may still be tinged with innocence. Again, context is the key.
What do these Spanish verbs have in common? They both change connotations when applied to objects or people. They can both be used to express perfectly innocent concepts, or to show physical or sexual desire. It's even possible to get the two confused: Te gustaría...? translates literally as "Would it please you to...?" but is more likely to be interpreted as "Would you like to...?" Sounds eerily like Quiéres...? or "Do you want to...?" doesn't it?
If you're still having trouble choosing between querer vs gustar, just remember that the subject matters. If you're talking about an inanimate object or concept, querer becomes want and gustar becomes like. But if you're talking about people, querer becomes love, in either a familial, friendly or romantic sense (depending on the context and how you say it). Think of gustar, when applied to people, as more like saying "please," as in "he pleases me," with all the extra interpretations the English phrase invites.