Different font (family and size) for one (cover) page

I would like to make a package for a title/cover page which should use a predefined font, whereas the document in which the package is loaded and used (used by using a command that generates a new page) should use whatever font it wants.

How may I do that?

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Font selection (family, shape or size) should be grouped to localize any changes. As reference, see Effect of changing \fontfamily and \familydefault.

Here's a mockup of using Bookman (pbk) for your title page, followed by regular Latin Modern (lmodern) for the remainder of the document:

\documentclass{article}
\usepackage{lmodern}% http://ctan.org/pkg/lm
\begin{document}
\thispagestyle{empty}
\vspace*{.4\textheight}
\begingroup
\centering
\fontfamily{pbk}\selectfont
{\Huge\bfseries My Title\par}
{\Large My Name\par}
\bigskip
\today\par
\endgroup
\newpage% End of title page

Here is some regular text in Latin Modern.
\end{document}

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