Tips are a matter of preference. The included Final Type E tips are one of the best tips out there. The Campfire foams are also excellent. Wide bore tips are good in practice, but I'm not a fan of the wide-bore tips that Campfire uses. I'm using the large Type E, but I'll probably experiment with the ML and M for different insertion depths.
Here are some other great tips: Symbio W, Sedna Earfit Xelastec (detail enhancing, secure as foam), JVC Spiral Dots. For foams I like Dekoni Mercury, but I'm more into silicone tips for feel and convenience. Spinfit also make good tips, including the best bi-flange tips, but most of the the I prefer Final Type E and Xelastecs on my IEMs.
Wide bore tips can enhance sound stage, but may also reduce definition.
Many people swear by Comply foam, but I find that they warm up the sound too much for me and suppress detail--I only consider them with very bright or very dry IEMs. The included Campfire foams have nearly no tuning effect, and Dekoni Mercury are similar in that they don't change IEM sound much, but they use a denser, springier foam that some may not find as comfy as Campfire foam or Comply.
For the Solaris LE, SE, and OG many folks find the shell size difficult. A custom eartip can solve this. Snugs in the UK can make a custom tip. Custom Art does this out of Poland, and I think Lear does this out of Hong Kong. I think all of them do worldwide service. I don't think you have to send your IEM to Custom Art or Snugs, but you will need to get impressions from an audiologist and send those. Snugs works with digital scans, so you may not need to send physical impressions, which saves on shipping if you go to audiologist who makes digital scans. I'm pretty sure that Lear and Custom Art need the physical impressions. If getting impressions, get them with an open mouth, with a bite holder in. This insures you can talk and eat comfortably with your customs in. Make sure your audiologist goes to the second bend. Ideally, go to an audiologist familiar with custom in-ear monitors.
In short, changing tips is one of the cheapest and most effective ways to do some sonic fine-tuning or to improve fit. I absolutely recommend doing it. Start with the ones in the box as they are some of the best silicone and foam tips out there.