Having more then 1 domain and site is something that I advacate for a long time. Instead of thinking company minded you should think produkt minded if you are selling online.
Being specific and narrow down the niche of your site. It makes it easier to market if your website is fi about mountain bike holidays in south New Sealand then if you are making a site about traveling in general. But what if you also sell traking packages in New Sealand…would you include it in your mountainbike site or do you think it’s better to have a new site?
My advice would be …spend $8 and make a new site. As those are your sites I see no harm in interlinking the two. Now the best thing would be if the two sites are on different servers. Search engines give points to various things and having links from different places is one of them.
So what if you have 50 topics all about New Sealand traveling and each has enough info to justify a site. That would mean that if you set up a network on different servers it would cost you 50 times the hosting accounts and have a hard time handling all the details with ftp, stats and managing it all . So when a hostingcompany I used and highly recommand send me an email that they had a new service called seohosting I was intrigued and had to look.
Seohosting.com is a Hostgator division and they offer plans starting with 5 different c-classes for $35 a month upto 50 different c-classes for $ 237.50. On each c-class you can have as many domains as you want so if you want to build more networks of interlinking sites this is a great deal as it makes it easier to handle it all and is cheaper then having dozens of hostingaccounts for $10 a month.
Using this service means that you can build your network of sites having seo in mind