What is the best way to have very good control over fonts?

Question

Embarrassing question, but I usually focus completely on layout and don't bother to mess with the font, except when I'm really feeling experimental and use libertine...

Anyway, what is the best way to have full control over a modern font family, like Helvetica neue, and be able to shift between, say, ultrialightweight and normal, at any size?

Is there any way to say \font{helvetica}{ultralight}{48pt} or something?

I'm sorry if this is a duplicate or bad question, but fonts in LaTeX are just something I've never understood.

Should I be looking into learning to use XeTeX or something, instead?

Answer 1

I don't know which is the best way, but with XeLaTeX or LuaLateX the fontspec package allows you to simply do that.

For example, if your document has 12pt using Scale=4 as in

\fontspec{Helvetica Light}[Scale=4]

should give you what you want.

Example:

\documentclass[12pt]{article}

\usepackage{fontspec}

\setmainfont{Helvetica}

\begin{document}

This is a very {\fontspec{Helvetica Light}[Scale=4] big} word

\end{document} 

Output

P.S. If you have an old version of fontspec the syntax

\fontspec{Helvetica Light}[Scale=4]

might not work. In this case use the old syntax

\fontspec[Scale=4]{Helvetica Light}