[Macka (Grant)]

Hi all, I need sound advice. I am wanting to get into astronomy and hoping to spark an interest in a couple of my children at the same time. I am trying to get equipped before our annual beach holiday and plan to spend some time learning the basics and getting the family excited about it.
What I had in mind is a scope useful for both terrestrial and astronomical viewing so we can use it both for viewing the many ships passing close by our position and sky in the evenings.
I am hoping however to bypass altogether the often dissatisfying first couple of purchases or even parts of a purchase where you end up needing to upgrade the areas where the makers have dudded the newcomer. I am an experienced hobbyist and tinkerer and know how this works but just don't have experience in this field yet. I would like the first scope to be one that I will still have in 20 years and love using for its intended purpose.
What I am thinking of atm is a really good 90-100mm mak cassagrain on a decent quality AZ mount but for as reasonable cost as possible. I think I would like to rule out any computerised models to be forced to learn manually and still haven't ruled out an EQ mount either. A question I have is can EQ mounts be easily adapted for terrestrial use. Also, I understand that balance, overhead use and eyepiece angle can be gotchas as well, but don't know when or how with what gear. I really don't want to make any intermediate purchases so if a certain component like the mount only starts to be considered worthwhile by experienced astronomers at a certain price point then that's where I'll be. Same with eyepieces I want to just go buy eyepieces that will never become my least favourite.
Am open and very grateful in advance for any assistance or advice.