Spatial statistics, like most statistical methods, is a large topic. If you would like spatial statistical theory presented in a statistical/mathematical framework my favorite is Cressie's book "Statistics for Spatial Data".
Since Diggle's point process book is out of print, A good alternative, specific to point pattern analysis, is "Statistical Analysis and Modelling of Spatial Point Patterns".
A great overview of spatial statistics in ecology is Fortin & Dale's "Spatial Analysis: A Guide for Ecologists.
For implementation of spatial Hierarchical Bayesian Modelling there is "Hierarchical Modeling and Analysis for Spatial Data".
I really like Gilks "Markov Chain Monte Carlo in Practice" for an introduction of Monte Carlo approaches.
For an introduction to geostatistics the standard is Isaaks & Srivastava's "An Introduction to Applied Geostatistics"
This is by no means a comprehensive list but are some of the books that I refer graduate students to.