Have there been any macro-evolution experiements?
Issue with the question

The question of what is an evolved phenotype that is "seemingly significant enough to the layman to be called macro-evolution" is very unclear and it makes it hard to answer.

Most experimental evolution are performed on lineages that have very short generation time (for obvious reasons) and on these lineages it is hard to even imagine the evolution of something that a layman would consider to be "significant enough to be called macro-evolution".

The whole issue is that one will probably consider a change in phenotype to be "seemingly significant enough to the layman to be called macro-evolution" if it occurs on lineages that have long generation time and therefore cannot be observed within a lifetime.

The question interesting. However, I think the best one can do is to look at the wiki article for experimental evolution who already offer quite an interesting list of examples. I tried below to highlight a few cases of eventual interest



Long term artificial selection on "large living things"

If one wants to consider artificial on "large living things", then probably artificial selection on crops and cattle will be a good place to look at. I think I don't need to list and make extensive description of how artificial selection has changed their phenotypes (and genotypes). Consider the pigs, banana and corn as examples.

A few evolved features that has evolved in labs in small organisms

We have observed evolution of multicellularity form unicellular organisms, observed new metabolic pathways and change in ploidy level just to cite a few major things that we evolved.

Lenski experiments

The Lenski long term experiments is the longest in lab evolution experiment performed today. They made a lot of different observations and not only the case of citric acid metabolization that you mention. Note that being able to metabolize a new compound is a pretty considerable evolved feature that only those who can't go further than considering evolution of extra legs as something significant would fail to appreciate.

Drosophila and Waddington's experiment

If one must restrict I suppose that looking at experimental evolution on Drosophila would be our best bet.

Change in allele frequency through selection is a relatively fast process. Creation of beneficial variants through mutations is often the limiting process. Cases where very different phenotypes exist in natural population and selection over these phenotypes (change in frequency only) will probably not be considered to be "impressive enough". However, one can consider Waddington's experiments (and further experiments inspired by Waddington's work) as an example of experimental evolution where standing genetic variance existed before the experiment started but was hidden in the environment they experimented (the exact process here might well be too advanced for a layman). Waddington in his experiments showed one can evolve Drosophila to have a double thorax or lose their halteres in only 20 generations.

Other Drosophila experiments

We evolved Drosophila to live in hypoxic conditions. It took about 200 generations that is more than 4 years. We have also selected Drosophila for cognitive abilities and food preference (and many other things).

Note on the term "macro-evolution"

The term "macro-evolution" hasn't been invented by creationists. It has been invented a long time ago, in 1927 by a russian entomologist. T. Dobzhanski and E. Mayr (two famous evolutionary biologist) have used this term without ever quite defining it. Because the term was never correctly defined, the vast majority of evolutionary biologist have either criticized the term.

It is true that the term is now sometimes used by creationist as any poorly defined term is one of the finest solution to build questions that can't be properly addressed due its lack of clarity.