To avoid floats, one option, as explained Martin H, is do not use floats at all.
But other is to use floats with the option "here": [h] or [h!] o even the more strict [H] (is this case need the package float) and even change the placement rules (see How to influence the position of float environments like figure and table in LaTeX?).
The advantage is that if finally place "just here" was not really such a great idea (specially if you later need add memorable happenings that were forgotten, ruining all the "good placements" below) it is easier allow a little float flexibility ([h] instead [H] for example, see note below), or a lot more flexible([tbph]), or change placements rules in the preamble, instead of modify the hard written code.
On the other hand, from what you say, I think a document class book without any special package is perfect for your travel journal, unless you explain what other features are looking for. However, you can use also a article class and use \section, \subsection and \subsubsection and even numbered or not \paragraph and \subparagraph for a more compact format. Depends on what you like. It's your decision.
Note: Contrary to what one might think, h option is flexible since it is changed to ht when cannot be placed in the page, as happen in this MWE:
\documentclass{article}
\usepackage{lipsum}
\usepackage{xcolor}
\begin{document}
\lipsum[1-3]
\lipsum[2]
\textcolor{blue}{\lipsum[2]}
\begin{figure}[h]
\centering\fbox{Imagine some graphic here}
\caption{Wanted between blue and red text, but here is better}
\end{figure}
\textcolor{red}{\lipsum[4]}
\lipsum[5]
\end{document}
If even then any rule is violated in the next page (more than 2 figures in the top, fill more than 70% of the height, etc.) the figure (and following also) wait for the top page and so on, unless the end of the article or the chapter is reach and then all unprocessed floats are flushed. Left several figures at the end might be acceptable or not, but when there are many figures awaiting their turn there a high risk of compilation error ("Too many unprocessed floats") that must be arranged with \clearpage commands here and there, changing LaTeX rules as \setcounter{topnumber}{3} or, better, allowing more floats options.
=)– Jake Sep 03 '12 at 13:56\captionof{figure}{Caption of picture}or\usepackage{capt-of}or\usepackage{caption}– Martin H Sep 03 '12 at 15:14\documentclass{holiday}\usepackage{duck}... sorry :-D – lpdbw Sep 04 '12 at 06:23